I see 3ms ping times between my friend and I on opposite sides of London, though we’re both on pretty decent broadband tech (me gfast, him some fancy hyperoptic plan). IIUC there are some ADSL technologies that add some minimum latency floor of 10+ ms. However the long distance stretches of backbone fibre shouldn’t necessarily add too much latency - e.g 100km of fibre at 2/3rd speed of light is an additional 1ms on your (two way) ping time