Jeez, I don't know.
I don't see why a manufacturer would build a rental binding to a lower standard than a consumer one. If anything, there are various reasons to build it to a higher standard (e.g. you're selling to a more-informed-than-usual and more-repeat-business buyer). Maybe they're not any sturdier, but I can't see why they'd be less sturdy.
While someone with a "who cares...it's a rental" attitude might abuse a ski in various ways, it's a lot harder to abuse a binding. Sure, I guess you could take a hammer to it. Why? Incidentally, some shops do look at the skis when they come back, and occasionally even charge people for repairs in appropriate situations.
I ski on bindings (some, anyway) that are older and have likely seen more ski days than a one-season-old demo ski.
If Look builds bad bindings (I don't know that to be the case), I'd stay away from Look generally ... and not just their rental bindings.