Drivers aren't paid while they're waiting though, right? It seems to me like this is just holding two separate jobs of the same type (which I don't think is uncommon for the types of positions one might have at Target or Walmart), with the only difference being more flexibility of which hours to work.
If you're a contractor hired to build a shed and it takes you 8 hours, you're there all day. But if you can build it in 2 hours, you get to go home, and you still get paid the same.
If you're a Target employee brought in to do inventory and it takes most people 8 hours but you finish in 2, you're only going home if you don't want to get paid for the other 6 hours. Otherwise you're going to be stocking shelves or sweeping floors or working a register until the clock runs out.
Driving works like the first one. If you can make a 45 minute drive take 42 minutes, you get to keep the other 3 minutes. (In theory if you can make a 45 minute drive take 15 minutes you get to keep the other 30 minutes, but good luck with that.)
