Wiring thousands of well cars for HEP to containers would be a huge expense, not to mention that the wiring would be stolen the first time the cars sat still for an hour or two. Same for car-mounted generators; they are also full of copper. The current situation, using containers containing diesel generators, seems to work well enough.

As to Amtrak, what is the alternative to HEP? Investing in a lot of power cars in order to have 2 or 3 on each train makes no sense, and each power car displaces one revenue car. One could also put a small genset on each car so it could fend for itself, but that is a huge procurement, installation and maintenance expense (ask any PV owner).