The upgrade path. AT&T had a very well worn path in place of constantly upgrade LA, NY and Chicago (often timed fed by federal dollars) and then trickling the previous systems down. This meant all cities were regularly getting their system upgraded whether it was worth the money or not but it really didn’t cost them anything since they constantly had systems to spare. Once the monopoly was broken it became a matter of accounting, the system was no longer primed with parts to spare, they now have to decide if this city is worth the money. Where I live has had 1 significant system upgrade since the breakup, and that was nearly 20 years ago. We’re not worth the money.
Then so be it. If it's not financially practical for AT&T to upgrade your infrastructure, then I sure as hell don't want a public utility doing it.
Here in New Jersey we have the opposite problem, where Verizon is deliberately letting its copper infrastructure go to sh!t in an attempt to force customers to fiber optic -- whether they want it or not.