We don't encourage infractions of any rules regarding the requirement of shoes in public places. We merely acknowledge the fact that everybody, even folks who have no desire or intention of making barefooting a way of life, likes to do this sometimes.
Hard core folks like Michael Sandler, barefoot extraordinaire who brought barefoot running into the public eye so that it is here to stay, will go barefoot just about everywhere.
Michael won't argue with the managers of a business who bar the door from him because he is barefoot, he'll simply leave.
Most public places in the USA have the choice to let patrons in barefoot or not. In most states, laws don't specifically prohibit barefoot customers. I admit that I tae advantage of the privilege in barefoot-friendly shops every once in a while in places such as Boulder, CO, but I don't gripe about such rules as society's rules are complex and the obligations for business owners are numerous.
Once in a while we all cheat. And folks who are supposed to enforce the rules may or may not do so. It may depend on the day, or whether the stories crowded, or whatever else.
All I'll say now is that rules are rules and there is no grand conspiracy I can see that is against barefooters. As countless barefoot advocates will say: be courteous when told to put your shoes on, don't act like a jerk. As with any group you might represent, if you act in a deliberately-discourteous way, you only give society the excuse to persecute you. Unless you like whining about persecution you brought upon yourself, such is a useless act.
Barefooting is about reducing impact on your surroundings, for the mutual benefit of everyone. So, wen you're slipping out of your shoes, do BARE that truth in mind!