I just bought a new 2021 Toyota Highlander in the Platinum trim. I ordered the vehicle through the dealer to get the color I wanted. When it was ordered we requested a trailer hitch receiver from the factory, and the order was accepted. The car that arrived did not have hitch receiver installed. There has been some discussion on whether a trailer hitch can be installed on the Limited and Platinum trims because it interferes with the hands-free kick sensor for the power lift gate which is placed under the center of the rear bumper. There is apparently a work-around now for the 2021s where the kick sensor is moved to the left and no longer interferes with the trailer hitch receiver. I saw a YouTube video from a dealer in Nashville, who showed a new Highlander Platinum with the re-worked hitch. https://www.youtube.com/watch?v=dWOhlQb0L0E
The dealer has no answers. I had the dealership issue an IOU at delivery to install the hitch if the parts become available at the price quoted at the time I ordered the vehicle. I contacted Toyota USA customer services who were not helpful at all and referred me to the dealer. When I got my post-sale survey, I brought this up again and submitted an email request to find out when replacement parts would be available. Toyota's response was that the trailer is not available for my vehicle. Can you tell me why Toyota would be stonewalling on this?
Check with your local UHaul dealer if you have one. They install permanent hitches.
Also you could search online, CURT hitches, for example...they may have their listings updated to show availability. I don't see where it would be a big deal to fabricate a bracket and move the switch.
Vehicle dealers don't like modifying anything that isn't manufacturer approved.
"Can you tell me why Toyota would be stonewalling on this?"
Because they want to make money, not deal with problems, just sell it.
Remember, "Toyota" is not Gods, they're human beings just like you and I, and a normal human response when faced with a problem is to walk away, get rid of it, "I'm not gonna deal with it".
That's what you are facing, and the only way to change that is to start applying force, as in complaints, calls, legal action, and don't stop.