> And what would be the point of a decal/video screen designed to trick people (Autonomous or not) into rear-ending your van?

There is a "popular" scam in China, where someone pretends to get hit by a car and then demands compensation. This occasionally leads to funny videos where they fall down too early and the car just drives around them; but I guess the scammers still make a profit.

Something similar could be done by luring autonomous cars into a crash and then trying to squeeze them for money.