Lidar generally operate by rotating a laser that pulses at a fixed rate, using optics to sweep the beam up and down to get a reasonable vertical FoV 360 degrees

Lidar generally operate by rotating a laser that pulses at a fixed rate, using optics to sweep the beam up and down to get a reasonable vertical FoV 360 degrees around the car. They output a stream of samples - basically a continuous series of timestamped (theta-rotation, phi-rotation, distance) tuples - that software can reconstruct into a point cloud. But! The lidar data is useless by itself since the car is moving through space at an unpredictable rate. Each sample has to be cross-referenced by timestamp with the best-estimate location of the car in order to be brought into a constant frame of reference. This location estimation is a complex problem (GPS and accelerometers get us most of the way there but aren't quite high-fidelity enough without software help) so it can't be done onboard the lidar. So to do what you suggest, the lidar would need a control system that allows its operational parameters to be dynamically updated by the car. But what parameters? Since the laser is already pulsing at least hundreds of thousands of times per second, there's probably not much room for improvement there without driving up cost, and if we could go higher we'd just do that all the time anyway. The only other option would be to slow down the rotation of the unit while it sweeps over the field of view we've decided is interesting. That way is a little more conceivable, but I doubt it would work out in practice. If the unit averages 10 rotations per second, it has to be subject to 20 acceleration/deceleration events, which would be a significant increase in wear and tear on the unit. It would also make it harder to reliably estimate the unit's rotation at any point in time, again driving up costs. All this can't grant you much more than, say, a 100% increase in point density on the road (assuming 120 degrees of "interesting" FoV and a 1/6th sample rate on the uninteresting parts). If these things are to be produced at scale, I imagine it would be easier to increase point density by just buying a second lidar, which would also bring better coverage and some redundancy in case of failure.