1) it's not cheap to produce lidars at a stable predictable quality in millions;
2) car driving training data sets for lidars are much scarcer (and will always be much scarcer due to cameras' higher prevalence) and at a much lower quality;
3) combined camera+lidar data sets are even scarcer.
It wasn't cheap to produce accelerometers at a stable predictable quality in millions before smart phones either. Mass production shakes things up somewhat. See the headline for reference.
2+3. BYD collects extensive training data from customers, much like Tesla does. They will have no trouble with training.