Everything has a user experience. A hammer, a car, a ski lift: using it is easy and pleasant and intuitive, or it’s clumsy and hard to figure out and anxiety-producing, or (most often) it’s somewhere in between.
An apartment door is hinged on the outside and you can’t open it fully without backing up and taking a step down the stairs. The SUBMIT button on the web form is on the left instead of the right, and a sizable number of users cancel instead of proceeding. These are completely different experiences, but they’re engendered by the same fundamental mistake: Whoever built the interaction didn’t think all the way through the user’s experience before they created the affordance.
Once you’re making something, the primary consideration is ease of building, not ease of using. And for good reason. Building is expensive and time-consuming, and it sucks up the lion’s share of your budget. You want your carpenters or developers to focus on working as efficiently as possible. If the door is easier to install swinging out, and you can do it with two workers instead of three, you install it swinging out. If you can reuse some code that you already wrote for a form, you plug in the old code.
That means that thinking through the use of the thing has to happen first. It’s a design process, not a revision process. Unfortunately, UX and IA—the disciplines that think through the use of the thing—are largely considered luxuries. If anybody ever thinks about user experience, it’s after a prototype, or a beta, is already built, and by then it’s too late to fix any but the most glaring mistakes.