Show HN: Share wishlists with your family
gifts.housejeffries.com
gifts.housejeffries.com
Near the top of the page, a message will appear suggesting that they lock down their account with a password.
So to answer your question, nothing but knowing the user's email address stops someone from logging into their account.
2) You can create a group of your family/friends, giving everyone a single place to look for multiple people's lists.
Whether that's enough of an advantage to negate the ease of purchasing and trust with Amazon Universal Wishlist I'm not sure.
That said, I'm not sure if you can add plain text items to an Amazon Universal Wishlist. If you can't then this would work better for general requests (e.g. "chocolate" as opposed to a specific chocolate bar) and unique requests (e.g. "Sis, will you paint me a watercolour?").