You think college kids sit around doing nothing between classes? These days a lot of them know what they are doing instead of partying and drinking, they would either take more classes so they can graduate sooner, or they learn highly paid skills like coding, so they can find better jobs in the future. (we have a hard time hiring any new grad below 100k and some I heard got pouched away at 200k after 1 year). Why wouldn't they speed up their studies so they can make them sooner?
For the same amount of effort truckers are doing, the good paying jobs would end up paying 200k+ after some training. If you have to get CDL then why not study well in school and get a good tech job? Oh, you can work remotely and probably get a 30% paycut if you are not lucky, still better than on the road for weeks.
BTW, if it is so simple to train them to do these jobs why don't employers pay internship to train these guys then pay them enough to stay on afterward? No one wants to train anyone but they want to pay just minimal, already trained employees.