Making decisions, adult or otherwise, without consistency accross the board does not give the traveling public a stable, predictable situation. If you provide a chaotic range of choices all based on individual "adult decisions" you will have even more problems with the traveling public having objections to what is in reality a chaotic situation. It has to be equal all accross the board or you open up the entire system to complaints of favoritism, racial predjudice and so on. Some of those complaints will result in legal action with numerous suits. It has to be consistent accross the country and as equal for all as you can make it.
Rules and regulations that are the same make for less stress for those involved on both sides of the system. Kind of like traffic laws and regulations instead of relying on the operator to make an "adult decision" about which side of the road they will drive on and at what speed they decide.