One of the malls where I live has a slot for you to put a credit card to go to the toilet. So not only do I have to get hosed by a thousand different ways malls suck my wallet dry, I also have to pay for taking a dump? Nah, I don't think so.
The restrooms at most malls and train stations here cost €0,70, but they're also manned by a cleaner for most of the day, so they're always clean.