While home users can (mostly) change their DNS resolver, the vast majority of them don't.

In a talk last year at nog.fi Alain Durand from ICANN dug down on DNS resolver usage: https://nog.fi/event/1/contributions/6/attachments/2/3/eu-resolvers.pdf

The findings are somewhat interesting, this does mean that "Geo"DNS driven things are still very possible, and actually a reasonably small majority of eyeballs need special casing for public DNS recursors that are more hostile to GeoDNS like Cloudflare's 1.1.1.1

Obviously the kind of user that changes their DNS to Quad1/Quad8/Quad9 is more likely to also know how to complain if they are being served content from the wrong place, but again it's worth keeping that in mind that most consumer users don't change their DNS.

Biz's however do seem to change their resolver, I assume because they are doing more of the configuration themselves (vs a home user that just has a router with all of the stuff configured out of the box), and are more likely to enter into config DNS recursors that they remember the address of.