In my experience, that's culturally exclusive to the upper-middle and upper echelons of society. In working class groups, no single person is expected to pay for everything; it's split relatively evenly.
It's absolutely cultural. Within Hong Kong culture (a close friend is Cantonese), there's this funny thing where people fight to pay the bill. You typically get points for doing it before anyone else even has the chance. Sometimes a person will get up to "use the restroom" then go pay the bill away from everyone else. It's seen as a privilege and an honor to be able to pay for everyone. Considering that in the family, we sometimes go out to seafood places with a dozen or more people (all family), it can get expensive. It's a bit of a show-off thing IMO, but the family is not obnoxious about it (no one actually tries the bathroom thing with us; they just joke about it...but we also never ever split the bill or even show it around or let anyone else see it).
My family is not upper middle class but if you try to pay for everyone, you'll find someone else has already slipped their card to the waiter. I've seen relatives almost get into arguments because two people insisted on paying.
Outside of my family, I've also had friends from relatively poor backgrounds insist on paying for lunch or drinks before. And I've had wealthy friends act extremely petty down to the penny. So overall I've found it's hard or impossible to generalize too much.
I think it's simple common courtesy that the person extending the invite picks up the check.