I'm fairly sure the reason Tesla didn't start with Lidar was that it didn't fir their strategy.
The strategy is
- Put the hardware on all cars
- Collect data and statistics to advance AP/FSD
Lidar simply didn't fit in this strategy. You can't put Lidar onobstrusively on commericial cars (esp. ones that are meant to be sleek and appeal to people who will pay 100k for them). And of course they cost a lot.
Now, if all of a sudden if we have inexpensive lidars that can be hidden like the cameras - it would be possible to put them in cars consistent with strategy - but Tesla will have a problem with 500k cars they have sold without lidars. So, at this point Tesla won't put lidars unless they think it is impossible to get to FSD without lidar (which is obviously not correct, given we all drive with just vision).
Basically the lidar ship has sailed, better to just concentrate on vision.