I think here you've missed the plot here completely. It has been explained, in fact you explained it with multiple examples in the first part of your article. It is NOT considered OK unless a woman subjectively thinks it is OK. Literally any approach from anyone anywhere could be subjectively considered inappropriate. In this environment it is very rational to simply not approach. In fact even an apparent invitation to approach that you suggest is still suspicious and can blow up in a man's face. It is simply better for most men in most situations to not approach.