Running a cell off a giant metal box? Probably not best for signal.
Most of them have been sold off.
Those that haven't was for a reason (nobody wants them, because of whatever lease/land-rights/obligations/service they have).
Plus, they're all at ground level.
It'd cost thousands per box, would supply... what? A few dozens of people, in maybe a couple of hundred metres. And, as pointed out, would probably get quite slow and unreliable backend (copper cables that have been there for decades) for all those users. One 4G user can pull 10-50Mbps easily without even trying.
On a "cost per potential user" case, they just wouldn't be worth the money compared to one huge massive cell tower in the next town.
Biting the hand that feeds IT
