Good observation, I honestly don't know how it works, except factory software does usually update right away. Mine did while putting on my license plate.
I think the biggest issue is camera calibration. Who is gonna calibrate these cars?
They could have a few ready to go for a test drive. However, how many people know what calibration is with their first Tesla, which they will need to complete before having fsd. Most of us are Tesla nerds know all the things to do. A first time owner, not so much.