There are industry standards for this stuff. ISO 21448, UL-4600, UNECE R157 for example, and even commercial certification programs like the one run by TÜV Süd for European homologation. It's a deliberate series of decisions on Tesla's part to make their regulatory life as difficult as possible.

Drive it in larger and larger closed courses. Expand to neighboring areas with consent of the communities involved. Agree on limited conditions until enough data has been gathered to expand those conditions.

While controlled conditions promote safety, they do not yield effective training data.

That's how all autonomous testing programs currently work around the world. That is, every driverless vehicle system on roads today was developed this way. You're going to have to be more specific when you say that it doesn't work.