No, garage floor is not even at all, even a skilled concrete layer cant level the concrete properly.
with my 5 foot, I use bits of metal to shim, but with the 12 legs, you cant do that, so the feet is designed so you level out the 4 corners and then bring down the rest so they are all level, very effective.
on my sump frame, I have just found that one corner raises almost 1cm from the other! that's how uneven the floors can be.
that's why my old sump cracked on the floor