Waze Rider and Scoop are actually pretty great for matching people up for carpools (and are specifically for that purpose and that purpose only, unlike Uber Pool/Lyft Line), and yet I don't see a large number of people using either service.

I suspect people with cars are still very protective of their ability to completely control their schedule; agreeing to ride in someone else's car makes it difficult to run errands after work without first stopping at home to pick up the car, for example. And what if they have a ride scheduled for 5pm but find out at 3pm that they need to stay later? With enough scale it shouldn't be hard to find an alternate ride, but we're not to the point where people can expect that to be easy.

I think people could definitely rearrange their lives a bit to make this better, like planning to run errands on weekends, or close to home (instead of work). Or setting reasonable boundaries with their employer (I'm scheduled to leave at 5pm, and not a minute after -- unless you want to pick up the tab for a taxi). But people are selfish, and stuck in their ways, and would, for some reason, prefer to sit in traffic.