They are aware. That's why you get 20Mbit/s, maybe 50 if you're lucky. Cheaper in the short term and it's not like you have a choice.

AFAIU, GP is talking about FTTC (or VDSL), which is moderately faster than typical ADSL via existing phone exchanges or (far away) cabinets, while being much more expensive. FTTC can be cheaper than FTTH, but silly IMO - any increase in bandwidth will be expensive.