My block of flats is small, only 6 flats, one of which is permanently unoccupied, and the uplink to the building is only (presumably) one gigabit symmetric over fibre into a Huawei switch (definitely fibre but I'm not pulling the SFP to find out) which then has copper ports for each flat. Other places will differ.
Yeah the bandwidth required for 6 vs 20 flats is completely different obviously

In contrast, on my new place's gigabit FTTP, thanks to the 'joys' of PPPoE my new Ubiquiti UDM Pro can't even achieve gigabit downstream due to well-acknowledged problems with PPPoE on gigabit lines. This is not going away any time soon for all FTTP delivered using Openreach infrastructure, so if you can get Hyperoptic don't delay on ordering as they don't use PPPoE. The uplink on Openreach is only 115 Mbit/sec unless you pay hundreds per month, the network is intentionally oversold with less bandwidth to premises and every equivalent package is much more expensive.
Not that I rate PPPoE, but that's a Ubiquiti firmware problem to resolve lol. Other router manufacturers can manage 1Gb no problem...
Also, of course Openreach oversell to the consumer market for broadband just like every other wholesale ISP does, that's what leased lines are for! It's not economically viable to supply every customer with their own dedicated pipe (hence leased lines).