Glad you brought this analogy up. In the case of the stop sign, everyone knows the rules, even if they choose to totally ignore them. In the case of the non towered airfield, it gets a little fuzzier as is evident in all these threads. In the case of the stop sign, my 20+ years of living in Oakland taught me that a certain percentage of the population in a given community don't give a damn about the rules if they know no one is looking. People flying airplanes aren't any better.
If we're to lose all the Class D towers as some here seem to think is long over due, I say if we must, then make the standard AIM advice of entering the traffic pattern on a 45 and the pattern itself, a rule. Make it like the stop sign, where everybody is at least instructed what you're supposed to do and that there is liability as well as consequences if you are caught failing to live by those rules.