you never see a truck scale on any road in Mexico
I agree - but it is almost never - I have very rarely seen Gov't portable weigh stations stopping trucks - very rarely. But there are scales all over Mexico - bascula 80 ton signs lots of places. Trucks do weigh. I would have no way of knowing how many weigh or why. But there sure are a lot of them that don't appear to worry how overloaded they are.
I don't know all the specifics but many of the cuotas are privately owned - or they were - some have been taken back by the Gov't. Corporations are formed by several companies and they make a deal with the Gov't to build roads and charge tolls - they get a 20 or 25 year deal and then the Gov't gets the road if they want. It does get complicated. Anyway - I have read that it is a failed idea because the tolls are so high few Mexicans use the roads and the corps. don't keep them up. In recent years the Gov't has been doing a great job of rebuilding and upgrading and improving the libres. Of course not all of them but we do drive a lot of libres in a lot of areas where the roads do seem better - and obviously cheaper for us.
Roads in the US are in sad shape too. When I was a trucker roaming 48 states in the 70s and 80s the roads were much better. Now roads crumble and bridges fall down and all we hear is cut spending. When Ike came up with the Interstate idea back in the 50s I am not sure anyone knew what a great economic boon they would be. As a trucker and now an RVer I have traveled all over the US for many years. We see the trucks - how many - roaming all over - millions. And we also see the weigh stations and know the rules. But the US roads crumble too - though not yet quite as bad as Mexico in most places - there are still some roads that will shake your teeth.
We will head toward the border - Laredo - in a couple days and are not thrilled knowing some areas we are going to bump along the way. But we will survive - I hope.