>I mean you can try, but they're going to take off. Unlike a vehicle, they're just going to dodge between cars and run up embankments.

This. ^^^^ If the cops try to pursue, and the bike/ATV takes off, they might cause exactly the kind of accident we're seeing in the OP here. I mean, they blast through red lights and stop signs when the police AREN'T chasing them. Imagine what they'll do if they think the cops are about to impound their bike?