On one side, it can't route through a bunch of valid paths. I first assumed it could be because of residents asking Google to cut traffic, but sometimes it's not even through residential areas. I see routes on the map that are avoided in favor of bigger loops, and when trying the shorter routes they're perfectly fine. Or perhaps it's the vehicle size and they optimize for SUVs ?
On the other side it will happily route you through paths that are restricted to specific categories of cars. It's up to the driver to carefully avoid them, but it really wants you to go through and reroutes you there when you deviate, so it's a huge PITA in areas you don't know and try to navigate while ignoring the navigation instructions. Cops seem to have noticed it, We've got fined the first time we fucked up, and now that I'm aware of the issue I see the cops in many of these spots basically waiting for the jackpot.