I work on these diesel trucks. Whatever they're charging, it's worth it. Since the gov demanded new emissions regulations in ~2008 it has become prohibitively more expensive to maintain these vehicles. Probably 70% of the work that I do has to do with the emissions equipment. You can have a perfectly functioning vehicle but if the emissions system has a problem, or even thinks it has a problem, which it often does, it will derate the vehicle and it has to be grounded, towed away and repaired.
Now imagine you cut your fuel expenses in half (probably more in mountainous regions) and your maintenance and downtime budget by ~70%? Yeah that's very attractive.
There's also a safety aspect. If you live in mountainous regions you'll see runaway vehicle ramps. Just short uphill roads filled with gravel and other substances meant to slow, like they have on the side of race tracks. That's because the brakes can actually overheat on long descents and stop working, which is obviously a huge and terrifying problem. EVs not only solve that problem with Regen but also turn all that heat back into energy.