Interesting Theory: The ramps are too steep for the speed at which the cars are loaded, thus they bottom out, sometimes causing problems that cause a car to start on fire. Once one car starts burning the problem is difficult to deal with, most especially with EV's.
Expansion on what the What's Up With Shipping" guy said on a YouTube I watched today. I have certainly heard before that loaders have become sloppy in their efforts to load ships fast.