You CHOSE to sign a two year contract with your carrier - not with Apple - so they would finance your phone purchase.
You cold have purchased a full price phone with no contract.
Ummm, no I didn't, despite your assumption. I haven't had a subsidised contract phone since 2006. It's not specifically about me or you, believe it or not. The majority of people may not have the funds to buy the phone up front, or it may not be the common model in a particular market due to carrier's anti-competive stance on phone unlocking, or because carriers choose not to offer reasonable SIM-only deals, which make buying the phone up front a bit pointless, or because the phone manufacturer decides they don't want to sell unlocked phones due to commercial terms with carriers. There are many valid reasons why many millions of people worldwide sign contracts every year. Perhaps some of them could have chosen not to, but many probably could not.
Anyway none of that is particularly on topic, except for its original point which was that comparing a phone, which the vast majority of people sign a contract for, with general use of bricks and mortar stores, is patently ridiculous.