I’ll give you an example that is already old: in early 2019, I was in Santiago, Chile while on a long bike tour. I went to Calle San Diego, a street that was famous for having a couple of dozen bike shops in one area. I was unable to find replacement pads of the sort that slid into e.g. Shimano’s LX or XT rim brakes. Some shops only had replacement pads that came with the whole metal apparatus for e.g. Shimano Deore. But most shops had no replacement pads for adult bikes at all. They showed me those blocky rim-brake pads suitable only for children’s bikes and said “This is all we stock now. Everyone’s riding disc brakes now. You’d have to special-order.” FWIW, I had been told the same thing in northern Chile earlier on that journey.

> Disc brakes are pretty fancy all things considered

This hasn’t been true for a while now. I have noticed that many – if not already most – of the Chinese BSOs at hypermarkets have disc brakes installed.