You can further optimize the setup by not installing engines/motors in all of them. So maybe you have one car providing locomotion, with the rest following behind and designed for carrying.

Maybe we can do away with the expensive battery if we feed power to these cars using overhead cables.

In the original Sim City, having your city entirely use tracks instead of roads was superior because there was no traffic congestion from tracks

If you're happy to put those tracks on every road, sure. I wonder why no-one's bothered with that before.

Fast forward to blackjack and hookers.

It's tedious to see these same sarcastic comments on every self driving car story. Yes. Buses and trains exist.

When you link the cars together, they usually switch to a hub that's a 10-15 minute walk from your destination instead of your destination and the compartments are occasionally shared with unstable and violent people, which while possibly "efficient" in some metrics, are downsides that many people would rather avoid. Personal compartments are a real differentiating advantage.

Slot cars at the grown-up level.

Maybe even put them on steel wheels on steel tracks, to make them more efficient.

Rugged American Individualism and Capitalism doesn't allow us to have things like that. We must always be in our individual bubbles away from the filthy poors.