"In this instance I'd say that if autopilot was engaged it likely got confused by the road markings which has just added a split for the right turn lane."
This one of the reasons I can't see fully autonomous cars working reliably on the roads. There are many, many examples for junctions where, especially in queuing traffic, it's easy to get in the wrong lane. More specifically, where there are two lanes approaching a roundabout (UK in case it's not obvious) and when you get almost there you finally get to see the road marking in the gap between you and the car in front telling the left lane is for left turners only and you should have been in the right lane to go straight over. Once you solve that problem, you get to the next roundabout, move to the right lane, then discover at the last minute that THIS time, the right lane is for right turners and the left lane is for left and straight ahead.
York outer ring road was notorious for this until they eventually put actual road signs up where the road goes from one to two lanes on the approach. If I, as a driver who does 80,000+ miles per year can get that wrong, there's little hope for an autonomous car.
Here i the UK, road signage and road markings are pretty much standardised across the whole of the UK. I can only imagine the difficulties and potential confusion in the US where signage and road markings seem to be at the mercy of local road planners in far less regulated way, per city, per state and federal on the main highways.