2 - it's not true that "no-one else solved" this problem. If we define this problem as: have a self-driving vehicle which safely navigates its environment and does not endanger its passengers or the people outside. See the Waymo whitepapers: waymo.com/safety/performance-data
Ultimately, even if we agree that what Tesla is working on is orders of magnitude better than what's currently available from them, that might not cut it:
Let's assume that the current obstacle detection is 99% accurate... if the newer versions/improved models are 99.9%, 99.99%, etc. accurate...
we'll still have a 0.1, 0.01, 0.001%, etc of chance of an obstacle not being recognized. Tesla cars are a small fraction of those on the road, and there've been several deaths already. If million of Teslas will be sold, those small percentages will still mean a significant number of accidents and deaths caused by Tesla. If instead a Lidar reliably detects all obstacles, well in advance of the vehicle approaching it (and the car will stop/disable self driving if the Lidar becomes unoperable, e.g. due to bad weather)... it would be irresponsible to persuade huge swaths of the population to let a machine drive the vehicle, without providing the extra safety that a Lidar enables.