You mean unless you pay for a special policy? I think it typically comes with its own warranty. The replacement prices differentiate between in-warranty and AppleCare versus "out of warranty" price. Which seems to imply they do provide it by default, until it just expires.

They do state it is a consumable and that it should maintain a certain level for a certain number of recharge cycles. Of course not sure what kind of careful wording they were using pre-controversy. But obviously it should all come down to what they promise to be covering.