It is everywhere in new development. I remember Google buying tons of "dark fiber" capacity from telcos like 15 years ago; that fiber was likely laid for future needs 20-25 years ago. New apartment buildings in NYC just get fiber, with everything, including traditional "cable TV" with BNC connectors, powered by it.
But telcos have colossal copper networks, and they want to milk the last dollars from it before it has to be replaced, with digging and all. Hence price segmenting, with slower "copper" plans and premium "fiber" plans, obviously no matter if the building has fiber already.
Also, passive fiber interconnects have much higher losses than copper with RJ45s. This means you want to have no more than 2-3 connectors between pieces of active equipment, including from ISP to a building. This requires more careful planning, and this is why wiring past the apartment (or even office floor or a single-family house) level is usually copper Ethernet.
But telcos have colossal copper networks, and they want to milk the last dollars from it before it has to be replaced, with digging and all. Hence price segmenting, with slower "copper" plans and premium "fiber" plans, obviously no matter if the building has fiber already.
Also, passive fiber interconnects have much higher losses than copper with RJ45s. This means you want to have no more than 2-3 connectors between pieces of active equipment, including from ISP to a building. This requires more careful planning, and this is why wiring past the apartment (or even office floor or a single-family house) level is usually copper Ethernet.