My guess is simply to deter people from using it as their more permanent option.
Nevertheless, the phrase "I owe my soul to the company store" starts ringing in the back of my head.
$99 is steep. I found <$75 ABNB rentals in Moutain View.
If they're charging that little, there's some sort of massive caveat involved (I'm guessing there's a massive "cleaning fee"). That would be cheap for rent, never mind temporary accommodation.