The answer isn't that clear-cut for roads. Plenty of roads in BC - and presumably elsewhere in Canada - are paid for by private enterprises that use them to access resources.
The Coquihalla highway in BC used to have a $10 (for passenger vehicles, more for other classes) toll that was originally intended to pay only for the cost of construction (whatever that amounted to). It was kept going longer than necessary (ie. generated more revenue), and eventually discontinued. The toll could have been kept going but for the promise, I suppose. The route cut roughly an hour of driving time between Kamloops and Hope. What inhibits private involvement in roads is up-front cost, and lack of opportunities to create a route which attracts drivers willing to pay for convenience. The hurdle is easier for short legs - bridges and tunnels - that present opportunities to dramatically cut driving times.
A point of note is that the Coquihalla didn't have any tolled competition. If a mix of public and private tolled routes existed, I'd anticipate a few things:
- the public options would tend to be less well-managed, and have more difficulty remaining solvent
- the solvency issue would lead to some f*ckery by politicians and bureaucrats trying to favour the public options
- there would be purely ideological f*ckery, too, from the people who favour public solutions in principle
- the private options would generate different kinds of f*ckery - lobbying for subsidies and exclusivity, generalized grift