Because the entire world is designed around the human body and the way it moves. It’s theoretically much easier to introduce a humanoid robot into an existing workspace than it is to retrofit all the doors, stairs, etc. to allow a wheeled robot to move around.
I’m not sure that can be the case when it’s increasingly the case that buildings are built to be accessible by wheeled humans currently, often mandated by law.
That applies to public spaces, yes, but not ALL spaces. I’m on the board of directors for a small non-profit organization that expanded their facility a few years ago. We had to prove for ADA compliance that one floor of our facility was restricted in its use and not for public access. If we had been required to make it publicly accessible then it would have required an elevator, which would have been so expensive that it would have put an end to that expansion project before it even started. The public spaces are all fully ADA compliant. Those private spaces are not.
Also, like most building code requirements etc. the ADA only comes into effect with new construction or when the renovations to an existing property exceed a certain threshold (I forget the specifics). There are plenty of older buildings out there that aren’t fully ADA compliant.
I know people who live on 3rd floor walkups that were likely built 100+ years ago with narrow curved stairs as the only way in or out. If you want to replace a delivery person with a robot in places like that then wheels won’t cut it.
