Cars, being a mostly private affair, are not subject to the public access regulations of public infrastructure.

The bathroom is an obvious problem, and it also ties into problem # 2; the Americans with Disabilities Act. Cars and even minivans are not compliant with ADA without very expensive modification. Airplanes can afford long dwell times and dedicated personnel for people with disabilities, but as designed Boring Company/Hyperloop stuff can't accommodate this in a reasonable way.