LIDAR has seen many cost reductions as capabilities continue to increase. I don't know the area well enough to speculate how much optimization might be left.

> Or, is it just the philosophical difference over pre-mapping, and not doing so?

It seems to be a "burn the ships" style bet that the Tesla engineers will get to camera-only self driving first without having ever relied on LIDAR. It's equally as likely (or moreso) that Waymo could get there first with better ground truth data from the LIDAR.