- obvious, but large numbers of pedestrians and cyclists
- 2 way roads becoming 1 lane where the directions must take turns due to construction, deliveries, or the Uber in front of you stopping in the middle of traffic for a pickup
- resurfaced roads that don't have lines painted on them for weeks or months
- congested intersections where you'd probably need to wait 3 hours to pass through legally, so you have to just pull into the intersection trusting that traffic will clear when the next light turns green
- pittsburgh lefts need to happen for the sake of traffic flow sometimes
- sometimes you need to do very human and assertive "negotiation" to get into the lane you need.
- another comment mentioned Waymo cars just rerouting to the next turn when no cars would let them in. There are a decent number of situations where that will cost you 5-30 minutes of extra trip time
- you can disrupt traffic flow quite badly if you e.g. don't pull up to the crosswalk, and out of the way of cars behind you, while waiting for pedestrians to cross on a turn (humans are also bad at this)
- it's difficult to overstate how often cars/vans/trucks are double parked, changing the lanes available, forcing cars and bikes to improvise lanes. This isn't an occasional thing, this is a 10x on a 15 minute trip thing