The last 1% of FSD needs a teenager with 30 hours driving experience. (using the premise of your second sentence applied to the first)
A robotaxi is not like vibe coding multiple setups. You only get a split second in some cases to intervene.
The last 1% in FSD is an asymptotic challenge for AI to master. The last 1% in a CRUD app codebase is also an asymptotic challenge for AI to master.