There are usually three possible reasons for this:
1/
If the street is on coax cable, then the end of street could be more than the maximum distance away from the nearest cabinet (which maintains signal power).
2/
The nearest coax cabinet has run out of tap points. This can be resolved by replacing it with a larger capacity cabinet.
3/
There is a "civils" impediment to taking cable to the end of the street. This is unusual as when I've seen this occur it's jut a couple of houses where what's going on below the pavement prevents cable ducting from being taken to the house (and a drop point dug in).
Seph - ( DEFROCKED - My advice is at your risk)