I think that there was a law that a television screen could not be in view of the driver while going forward and this was interpreted to include rear-view cameras. I did a work around on my motorhome to display continuously and find it to be extremely useful. Why that would be any more distracting than a mirror I don't know. The laws may not be keeping up with technology.
The rear camera on my 2016 Ford goes off as soon as I take it out of reverse and leaves the zoom mode. It sure is annoying when I have to fine tune my approach to a trailer.
Sorry that I can't answer the op's question but I sure am sympathetic to it.