Just writing these down for posterity:

Changes lanes without real purpose. The car may not see far enough ahead to understand that changing lanes won’t allow it to make much real progress.

Needs to identify bad drivers and stay out of their way. Erratic drivers who can’t stay within their lane and cars driving too aggressively qualify.

Needs to avoid the trajectory of other cars changing lanes. The Tesla treats other cars as if they will do the “right” thing, so it likes to just zip on by other cars merging into the adjacent lane. In the real world, drivers are dumb and will sometimes keep changing right into your lane. There’s very little to be gained by assuming the other car is a reasonable driver … it makes way more sense to just slow down or speed up a little to allow the other car to do something stupid with no side effects.

Lane centering behavior needs improvement. Should stay more to the right on two lane highways. Should take into account like shoulder width when determining position within a lane … if you have more shoulder width, use that side of the lane more.