You'll have to provide a citation to support your assertion that "most people who sit at local ones...have free supercharging".
The use cases for SCs are myriad. There's a SC near my house; I never use it even though I have free SC'ing for life because charging at home is more convenient. I stop by there regularly (it's at a Target where I go anyway) and most folks I talk to there are from the greater twin cities area and do not have free SC. The needs vary: some are from out of state and are traveling. Some are from out of town but in MN, and while could make it home without charging, want a little boost before heading home. Some, as you said, live in apartments; my son is one of these folks, and while he has a 110v outlet for charging at his apartment, sometimes he needs a faster charge up. But he pays for it, too, no free SC on his M3. Other folks at the SC are those who put a lot of miles on just in town, and just want a fast fill up. Come to think of it, I don't think I've met anyone who *has* had free SC'ing at my local SC. There are probably some, but I think it's a quite varied mix even of the local folks. But that's just anecdotal based on my experience. Only Tesla really knows what the mix is.