This is the opposite order of operations, though. Your analogy is flawed. It's more like you I bought the house in the middle of the shop knowing that I had to use your shop. I also had full access to the policies by which you had run that store since its inception, with only minor, immaterial modifications. I also have and always have had the option to move to another, cheaper house with dozens of stores close by.
HouseOwner: Hi, ive just bought a new house here and I need a few things for it.
ShopOwner: Sure what do you need ?
HO: I need some lamps, a fridge/freezer, sofa, beds, oven, table & chairs, and a TV, carpets, bedding sheets, plates, cups basically everything for a new house. I did find it strange that I wasn't allowed to bring any of my existing items with me.
SO: Great, they will be in your house when you get home. And it's refreshing to hear that you read our Policies.
.........
HO: Hi, I was just in here earlier and bought a few things for my new house, but I've gone to sort out my electricity supplier and they say I have to buy it from you ?
SO: Yes, thats correct.
HO: So you will be my supplier ?
SO: mmm not really, they supply to you, you just pay us for it and then we give them 70% of that money.
HO: Soooo why cant I just get it from them then ?
SO: Policies Sir !, of which you had full access to, prior to buying your house.
HO: ok and if I need gas for my car ?
SO: Yes, you need to buy that from us too.
HO: Food for my fridge ?
SO: Yep.
HO: Water ?
SO: Of Course Sir. And if you want to buy TV packages to watch, thats through us as well. Basically anything you need for your new house you have to buy from us.
HO: I cant buy 'anything' direct from the companies ?
SO: No Sir, again I refer you to our 'Policies' that you were well aware of before you bought your house.
HO: That doesnt seem very fair.. or indeed legal.
SO: Sir ! Again I refer you to said policies and may I point out that nowhere does it say it's fair or legal.
HO: So it's Illegal then ?
SO: Sir, whether its Illegal or Legal is irrelevant, you were aware of the policies.
HO: Well that doesn't seem right to me, I think I'll sell up and move elsewhere. I suppose your going to tell me I have to pay for the removal company via yourselves as well ?
SO: Oh no sir, you're not allowed to take any of the items you purchased with you. Policies !
HO: Nothing ?
SO: Correct.
HO: Nothing at all ?
SO: Nothing, Zilch, diddly-squat, zero, Sweet FA.
HO: So, Basically I can only keep my stuff If I continue to live here ?
SO: Welcome to Apple, Home of the Walled Garden.