> Is it that hard to build stuff for the greater good of the public but respect mother nature and workers' rights at the same time?

It is, it takes political effort and most importantly it takes adequate staffing on the state/local government for supervision and proper tender processes, and both is really short in supply - one might say that the latter is done on purpose as an excuse to privatize yet another piece of public infrastructure.

Of course a private toll road company can build faster and keep up with maintenance, it doesn't have to deal with tender bullshit, it can hire enough of its own staff to make sure vendors don't screw them over, and if it's a large enough company they can hire their own construction crews. Oh and obviously it can provide a source of extra income for the grifter politicians that vote for the privatization...