Oh god, a utilitarian. A top-down philosophy if there ever was one.
First, I'd like to issue a three pronged challenge:
1. How is it that we share experiences? I do not see what you see. I do not feel what you feel. I do not hear what you hear. I do not taste what you taste. In fact, we each have independent subjective experiences because we are not part of a shared consciousness. Experience is tied solely to a conscious entity... and we are each independent conscious entities. (Note: the point here is best decribed by number of experiences... two separate experiences or one shared experience... not saying we taste the same thing different.) Perhaps you meant that we experience events in the world with each other? If so:
2. If we do not share experiences, how can the value of an action be determined outside an individual subjective judgement? You're arguing that actions can possibly have intrinsic value. I'd like to propose this series of questions:
How can we determine whether or not some object is good? In other words, something that is good must be good for something. It's fairly easy to determine whether a hammer is good. If it's good for hammering, then it is a good hammer. However, here we're measuring the object (hammer) to the task (hammering). In such a situation, it is indeed true that there is an objective means of determining whether the object is good, but let's take a step up. Nobody is foolish enough to deny the objectivity of instrumental value (your invisible car), but here my ultimate goal is to deny intrinsic value. So let's take a step up.
How can we determine the value of a task beyond relating it toward some other task? In other words, consistently applying instrumental value undoubtedly does not reach some end. A hammer is has value if hammering has value, hammering has value if (for example) building a house is necessary, building a house is has value if having shelter has value, having shelter has value if meeting needs of self preservation has value, (here going into serving other as the higher goal) meeting needs of self preservation has value if serving others has value, serving others has value if... well, that's the end of the road for you isn't it.
My question is: what gives this task of serving others value? More abstractly, what gives something enough value to live for... let's include every task we do. What standard of value is worth choosing over any other standard? Here, one cannot rely on instrumental value to give the answer... you have two choices:
First, claim that goals can only be evaluated according to an intrinsic standard of value.
Second, claim that goals can only be evaluated according to a subjective standard of value.
These are mutually exclusive... claiming one rules out the other.
To be clear, we've ruled out attempting to judge objectively under either standard according to instrumental value. It leads to circular reason as every end is also a means. Here we concern ourselves ONLY with the ends.
So, the big question is... is there any difference between the two claims? There is no notion of intrinsic value that can be demonstrated without resorting to self-evidence or axioms. To claim an intrinsic standard of value is valuable without resorting to an endless reduction via arguing through instrumental value is to make the essentially subjective evaluation that such a standard has value.
There is no essential difference!
3. This bring me to the third point. Ultimately, the highest value judgments - the ones answer the question, what is the good life? - as argued previously are essentially arbitrary. Of course, I'd like to call attention to a few things:
First, marginal point: I'm not about to let emotions like happiness determine (used technically; determine is being opposed to influence) how I live my life. If it was unsuitable in one situation, it is unsuitable in another. There is no good reason to consider any emotion as the final word in deciding how to live one's life. To be ruled by "true happiness" is no different than to be ruled by euphoria, but the real problem is that emotions are biological responses to the current situation only. They don't tell you a great deal of things about the future. I'm happy when I get drunk, but that doesn't mean I'll enjoy the next morning. Let's say I'm happy serving others, that doesn't mean I'll enjoy the fact that I sacrificed my time for them later.
Second, you ask, "Is it the drunken escapade that fills us with happiness or is it the enjoyment of sharing it?" Point 1 of this post reflect the conflation here, I enjoy it... We do not enjoy it. Maybe You and I enjoy it which is merely two subjective appraisals as opposed to one. In other words, you merely contrasted quantity of the same essential thing in your question, then moved to an entirely different type of thing. To curtail a possible counter, it is entirely logical coming from a stance of being concerned about my enjoyment to assign instrumental value to your enjoyment. You know, mutual benefit doesn't correspond to service to others. I'm still primarily concerned about my values and what promotes my values in a mutually beneficial situation.
Third, while I'm sure you may be tempted... the proposition that moral value is subjective and arbitrary does not imply the absence of rights or responsibility (although it does rule out moral obligations). This is due to the recognition of each agent as capable of individually determining the value of an object/task/goal. In other words, the structure of the entire position dictates the sovereignty of the individual... so negative rights still exist.
Fourth, the drunk driving thing is actually a big deal. Just because the law says that you aren't responsible for something doesn't mean that you aren't responsible for something. Let me put it like this:
Banning guns is placing all gun owners as responsible for the actions of one man.
Charging a drunk driver with murder is placing one man as responsible for the actions of himself.
The essential issue is who is responsible... the gun/vehicle or the man. I'm not saying we go banning cars or alcohol, I'm saying we don't ban guns. Drunk driving is essentially synonymous to taking a loaded gun and firing blindly a few times at an apartment building.
It's logically consistent to deny the responsibility of the drunk driver and blame the gun for someone being shot, but my position is pretty clear... the man is responsible for his actions: the alcohol, the car, and the gun are not.
Anyway, this all is intended to demonstrate that educating people in philosophy will not cause them to agree with you as though questions of value, morals, responsibility, etc. have all been settled beyond question. I'm modestly educated in philosophy, and I'm not sure how I could disagree with you more.