No one prevented other people from running their own AT&T phone company in the US. Except the lack of capital, and endless regulations with running telephone polls across the US.
Google even tried more recently to run their own fiber optics and gave up in the end because of entrenched regulations making it impossible to challenge the modern monopolies internet providers have.
It is not, even really stretching the definition, a state sanctioned monopoly.
This is a joke right?