You're absolutely right! Of course if you look at the MY, the exact same buttons are in the same place. One on the back of the seat, and one on the back of the hatchback. The hatchback one drops the seats - "at the press of a button". But no such luck on the MS.
Well, it is of little consequence most of the time. But it that little annoying (OCD) thing where we know how it was designed to work - look at the MY - and we see it doesn't work that way. Hopefully they'll fix it for the '22 MS so we can be in that "special" group.