The misleading part is that (in at least one common usage path), the site sets itself up to look like every other online shopping site. The kind that people expect to use by putting stuff in their "shopping cart" and proceed to "checkout" and pay once.
Think of the people in your life not quite as tech-savvy as yourself, like maybe your next-door neighbour or your mother. Would you expect them not to be misled by this? Sure, I'd hope my mother would be critical enough to notice, but I can easily see it happen otherwise.
Another indication is, I assume that a lot of people who do notice will instead decide to bail out entirely and not buy anything, rather than (like I would do, if I really wanted the item) pay, log in, and cancel the account immediately. Because that's not really an obvious thing to do, given the set expectation of being a regular online shopping store.