Oh Amazon was very very wise when they came up with and patented their one click purchase button many many years back. That button is dangerous when enough homebrew has been consumed. One simple click and the order is on its way to you.
The majority of other sites you wade through at least four steps for your address, payment method, etc. Every one of those steps being the opportunity it say 'eh I really don't need that' and stand down.
Oh man I've had stuff show up and wondered who the heck ordered that? And I look back and hm, strange, it was me, I did order that, ok well it must've made sense at the time I guess ...