These thieves have to steal from a moving vehicle? Sure it's not impossible, but it's more Hollywood heist than something you'd see in real life. It will almost certainly happen a few times, but for practical purposes the amount of stuff stolen before the guys are caught will be less than what it costs to hire tens of thousands of rent-a-cops to sit in the backs of trucks.

Plus, these are thieves we are talking about. Pointing a gun at a human driver and telling them to pull over so they can rob the truck is something that could easily happen today but is extremely rare. The minimum police response time is something that's hard to measure. It might be many minutes 90% of the time, but if you do 10 or 20 of these heists eventually you're going to get unlucky and the cop will happen to be sitting at a speed trap right there are you're busting into the truck.

This is the fundamental problem with crime. You will get away with it most of the time, but when you don't you're fucked. It's a lousy career choice because the upsides are modest relatively speaking, and the downsides are huge. If you're going to be a criminal the trick is to steal enough to retire on and then immediately retire. Knocking over one random truck is not going to do it.