While I applaud the idea of putting up the signs, I've made it an Instagram habit of posting pictures of people doing exactly what the sign prohibits, usually standing right next to the sign or under it (no smoking, no parking, strollers-only, etc.) I just assume that whoever it is (HKer, Mainlander, or otherwise) is illiterate.

It's quite an amusing thing and given how often it happens, I'm dubious of the effectiveness of putting up signs without some sort of enforcement (i.e. someone from CX has to periodically remind people of the signs).