I think a better analogy is that you simply recognize that you're on the side of the road where cars are zooming toward you instead of in the same direction as yourself. Now, a strict believer in the essential dichotomy between is & ought might not feel compelled to take any specific action in this situation, but someone who accepts induction into their thinking and is concerned with thriving in the world "ought" to take a very specific class of actions, given the "is" that's before him.Morality deals in principles.
Why should anyone feel obligated to obey an impersonal principle? If I'm driving on I-70 and I happen to see a random pile of rocks that I think spells out "YOU ARE ON THE WRONG SIDE OF THE ROAD!" should I get on the 'right' side of the road, and would it make any sense to praise myself for doing so or to blame anyone who doesn't? Someone (I can't remember who) has said that it would seem kind of odd if moral principles were just part of the "furniture of the universe".
As for it being odd that moral principles should be intrinsic to the universe, I'd say it's no more odd that mathematics, or "buy low & sell high", or the fact that time only flows in one direction, should be. Some things are just metaphysically given, and it's up to us to live within the world that we find ourselves in. <shrug>
And how can you have a standard in the first place if physicalism is true and we are nothing by genetically programed machines, offspring of the Big Machine? How do you get from there to here? Where there is no transcendent standard ethical statements and commands are meaningless, irrational and unintelligible. Brute physical forces that operate by chance or necessity do not have virtue, justice, fairness, dignity, or obligation.Here you're falling into the fallacy of composition trap. We're made up of lifeless components, but that's irrelevant because it's the complex entity as a whole (the "person" in this case) that's alive. Likewise, the quality of "wetness" doesn't apply to oxygen or hydrogen, yet water has lots of wetness. Where did the wetness come from when water molecules were formed from their un-wet components? Again, no conundrum to worry about.
While you have given a very good illustration of the composition fallacy, I think I am not committing it here. There are, as you know, various kinds of proffered causal explanations of the very complicated matter of mind and consciousness, i.e., why water is wet. The materialist seeks a causal explanation in the reduction of consciousness to a material property of the brain, an emergent phenomena that appears only at very high levels of complexity. It is presumed to be irreducible to lower levels even though those 'lover levels' alone do cause it. (unlike a liquid which is emergent but which is ontologically reducible in terms of the relationship between more basic elements.) The experience of things like the wetness of water is causally dependent only by the brain with the brain being basically in a new state of matter.
Even if this view were correct in explaining consciousness it is of no help at all with the problem of morality. It is not just an epistemological problem of calculation of the possibility of billions of firing neurons and what causes consciousness. Even if you could hypothetically explain all consciousness in terms of matter, you still are still saying that matter ends up producing real morality; actual, not illusory, right and wrong. Is matter or any of its emergent properties dualistic? Conversely, is morality just a property of human consciousness? If it is then it is entirely subjective, and not worthy of the name. How is it that even a "new state of matter" (still governed by chance or necessity) produces authoritative moral commands worthy of praise when "obeyed" and blame when "disobeyed"?
Cordially,