Personally, I don't understand the economics of lidar for self driving vehicles. 1) How many lidar units will one vehicle need and how much will this cost? 2)

Personally, I don't understand the economics of lidar for self driving vehicles. 1) How many lidar units will one vehicle need and how much will this cost? 2) How will noise from other lidar systems be addressed? Eg two or more disparate lidar systems on other vehicles using similar frequencies? 3) How small can the lidar systems be made while still being effective in real world use? These units being used for testing are massive and probably stupendously expensive!