Yeah I know....

I guess you could enforce roaming agreements like they do in the EU(?) but then you still would have carriers having to negotiate with each other when one carrier has more external roaming traffic with the other - like Internet peering arrangements.

I don’t have a strong emotional opinion either way. Just trying to come up with pros and cons.

Breakup by region would not increase competition from the perspective of most consumers. They would have the same number of options.