If I sell you a garage for 2 bucks a month, you might wonder but you will probably take the deal. Then you come around and notice that someone else is already standing in the space I sold you, and I tell you that you're allowed to use that space to park your car but only when it's free. Would you be happy? I guess not.
thats a great way to highlight how you should read the contract you sign when purchasing a service. Apparently, the garage you are operating is only for people to stand in, not park cars. I tells ya, I would be some ticked if I rolled into your garage with this huge smile on face because I just found the best deal in the world..monthly parking for 2 bucks!! wooohoo! then as I go to pull into my new spot.. I see that there is a guy standing there. I honk the horn and try to wave him threw..but he just stays..sipping on his coffee and shoots me a dirty look. so I honk again..and he yells 'this spot is taken..find another!'.
(I realize that you probably meant that there is another car parked in my brand new spot..but I just couldn't get that picture out of my head. a guy just standing in a car-sized space in garage. haha)