Nobody's ever going to be able to remove gravity, silly bloggers. And Railroad's are never going to pay the expense to regrade/ re-level industrial sidings and the infinite places to spot RR equipment. That'd be insane. They'd go bankrupt paying the expenses for doing even just half the sidings. Instead, they'd use strategically placed derails, in a multitude of places. This would offer them the flexibility to park cars anywhere they needed between derails, instead of requiring they place cars only "Here" and only "There."
But at say.... $2,500 apiece or so, that also costs alot of money. In addition to the fact now you have a bunch of damaged equipment, or at least a cleanup expense, each and everytime after a derail does it's job.