Waymo is using full lidar and other sensors, whereas Tesla is relying on pure vision systems (to the point of removing radar on newer models). So they're solving a much harder problem.
As for whether it's worthwhile to solve that problem when having more sensors will always be safer, that's another issue...
While it ought to be possible to solve for just RGB… making it needlessly hard for yourself is a fun hack-day side project, not a valuable business solution.
They may well best Tesla to this, though.