1) That's why we have human rights and lawmakers who are supposed to act in the best interest of the people - to protect people against unfair contracts like that.
2) Your plan would introduce vast inefficiencies (way worse than the government) into road building and maintenance. If people are duplicating roads to compete for lower prices, they are putting in way more capital expenditure than is necessary. The reason there is a forced monopoly on things like roadways and utilities is because it doesn't make sense financially to have multiple companies competing for the same thing - the recovery of capital outlay would require prices much higher than is seen today. Instead of me paying $10/month in local taxes to maintain the roadways near me, I might be paying $200 in fees throughout a month of driving on some cobbled-together private road system.
1) "supposed to"... except the very existence of those lawmakers and the system which supports them
is an unfair contract like that.
2) Only if someone were to do something like this, blocking off roads, rather than running them for max efficiency. If it didn't make sense for there to be multiple companies competing, there wouldn't be a need for a forced monopoly, one would develop naturally.