Completely different problem domains. A mobile phone is interacting with a fixed point (i.e. cell tower) that coordinates and manages traffic across cell phones to minimize interference. LIDAR is like wifi, a commons that can be polluted at will by arbitrary actors.
LIDAR has much more in common with ordinary radar (it is in the name, after all) and is similarly susceptible to interference.
No, LIDAR is relatively trivial to render immune to interference from other LIDARs. Look at how dozens of GPS satellites share the same frequency without stepping on each others' toes, for instance: https://en.wikipedia.org/wiki/Gold_code
Like GPS, LIDAR can be jammed or spoofed by intentional actors, of course. That part's not so easy to hand-wave away, but someone who wants to screw with road traffic will certainly have easier ways to do it.