It’s likely even simpler than that. Animals live mostly by instinct. Predators usually sneak up on live prey and chase it, whereas scavengers will happily eat animals that are already dead. I’m willing to bet that the “play dead” strategy backfires spectacularly against vultures, for example.

It doesn’t take more than an encounter with a house cat to see how their hunting instincts work. They’re just not triggered by dead things.