Waymo is trying to solve the environment. They're HD mapping every centimeter of areas they operate in, so that they can let their vision systems focus on deviations from that single source of truth. It's a reasonable approach, but it has some significant limitations, especially in terms of infrastructure.

Tesla, on the other hand, is trying to make their cars work anywhere. It's a larger problem space, but the end goal is a far more robust product, with much lower long-term infrastructure spending.

I personally like the robust approach, but I think both approaches are long-term viable, albeit for different use-cases.