Because LiDAR uses moving parts, it is easier for it to break or malfunction and, thus, more expensive to maintain. Radar has no moving parts and is cheap to replace.

What makes LiDAR so expensive?

Each laser had a matching detector. The complexity of this design and the need to precisely align each laser with its corresponding detector was one reason Velodyne's early lidar units were so expensive.

How much does LiDAR cost?

Musk has shown such distaste for lidar technology mainly because lidar sensors have been so costly, with a system for one vehicle costing as much as $70,000.