It's the same in the US. The ISP fiber network falls inside their security boundary in my experience - you can't BYOD. They install a modem (these days often including an integrated router, switch, and AP) and you receive either ethernet or wifi from them.
I think the only major change in that regard has been that coaxial cable providers here will often let you bring your own docsis modem these days.
I never found any of this concerning until quite recently. With the advent of ISPs providing public wifi service out of consumer endpoints as well as wifi based radar I'm no longer comfortable having vendor controlled wireless equipment in my home.