The NHSTA hasn't issued rules for these things either.

the U.S. gov has issued general guidelines for the technology/industry here:

https://www.transportation.gov/av/4

They have an article on it discussing levels of automation here:

https://www.nhtsa.gov/vehicle-safety/automated-vehicles-safety

By all definitions layed out in that article:

BlueCruise, Super Cruise, Mercedes' thing is a lvl3 system ( you must be alert to reengage when the conditions for their operation no longer apply )

Tesla's FSD is a lvl 3 system (the system will warn you when you must reengage for any reason)

Waymo and Cruise are a lvl 4 system (geolocked)

Lvl 5 systems don't exist.

What we don't have is any kind of federal laws:

https://www.ncsl.org/transportation/autonomous-vehicles

Separated into two sections – voluntary guidance and technical assistance to states – the new guidance focuses on SAE international levels of automation 3-5, clarifies that entities do not need to wait to test or deploy their ADS, revises design elements from the safety self-assessment, aligns federal guidance with the latest developments and terminology, and clarifies the role of federal and state governments.

The guidance reinforces the voluntary nature of the guidelines and does not come with a compliance requirement or enforcement mechanism.

(emphasis mine)

The U.S. has operated on a "states are laboratories for laws" principal since its founding. The current situation is in line with that principle.

These are not my opinions, these are all facts.