Bingo. Why would a foreign business care? All they want is something that looks like a UKARA so that the package doesn't get bounced right back to them.
Aside, I just asked the Home Office how many UKARA checks Border Force performed last year, and the tl;dr answer was "Don't know, won't find out for you."
I strongly suspect that means that there is no systematic checking, and you'd have to be very unlucky to have your RIF spotted by Border Force, let alone having the UKARA actually checked.
I'd stress though that in the case of import, the risk is on you.