Do you have a citation for Cruise being at Level 4? I’m very skeptical of that. Friends of mine at Cruise have privately told me they’re still working towards Level 4.
I think the NHTSA documentation is also insufficiently precise.
I don't have any citations beyond what is in that medium post which should be enough to indicate it is level 4. Level 3 requires a driver to be available to take immediate control of the vehicle. The simple act of sending a car out on a road without a driver shows the car is level 4 (or the company is wildly irresponsible to try it and the state is wildly irresponsible for granting the permit, but hopefully we can rule these out).
I think the NHTSA documentation is also insufficiently precise.