My experience is that this is largely true only of the biggest ISPs in the US and Europe that were around in the 90s and have IPv4 in plenty. In other countries

My experience is that this is largely true only of the biggest ISPs in the US and Europe that were around in the 90s and have IPv4 in plenty. In other countries or even with other ISPs I see fairly frequent turnover. Agree it’s not the biggest deal but it is a pity and something the protocol stack around IPv6 should support (daily/weekly randomizing of prefix unless someone needs the stability). The vast majority of modern devices and usecases get no additional value from being stably addressable from the internet.