No, a very small part of the last mile is connected by fiber. Trunking is always fiber these days. As are local neighbourhood branch points, if your provider evolved from a telephone company. (If you live in an apartment building served by an ex-telephone ISP, you likely have fiber run all the way to the network closet of your building, with only the per-subscriber in-wall wiring switching over to copper.)

ISPs that evolved from cable companies might still be using cable hubs with a common collision domain, but only a relatively small number of subscribers will be riding the same copper — it’s just cheaper these days to convert the signal to fiber as early in the signal path as possible. Plastic wires are cheaper than metal wires, and you need fewer of them (and so fewer switches.)