> They use that uploaded data to test their FSD software to see if it can handle that particular route, and tweak it as necessary to either handle places it was having trouble or to hard-code special rules.

This is an approach that is doomed to fail, because trying to hardcode the particulars of a specific route will converge to working pretty well until the moment something completely unexpected happens which needs human-level AI to be able to handle in the moment.

This is why level 5 autopilot isn't really going to happen without the invention of real AI, which is debatable whether that'll ever be achieved. Most certainly not in any of the timeframes Musk keeps promising.