Waymo chose the more expensive but easier option, but it also limits their scope and scalability.
I don't buy it. The lidar data is useful for training the vision models, so there's plenty of reason to believe that Waymo can solve the vision issues faster than Tesla.
BYD was just a cell phone battery company, and was like "well we've got the lithium supply chain locked down, you know what needs huge batteries: guess we're doing cars now."