Amazon is a bit tepid when they try anything too novel(their phone went from flagship pricing to free-after-contract how fast?); but they have three basic virtues that make them a terrifying force to be reckoned with:
1. Cultural disinhibition: They started selling books; but never seemed to have fossilized into the 'We are a bookstore. I can see maybe expanding into selling some bookmarks, or paperweights; but hand tools? How absurd!' model. 'Books' was merely a special case of more or less rectangular objects that are legal to send through the mail. They've since expanded into an ever larger collection of more or less rectangular objects that are legal to send through the mail, without much concern about what they are.
2. Adequately competent implementation: Remember 'Microsoft PlaysForSure', the killer ecosystem of hardware, software, and a competitive marketplace of music sellers(almost always cheaper than iTunes)? No? That's not very surprising, they don't really deserve to be remembered. How about 'Ultraviolet', the 'cloud-based digital rights library' that is somehow associated with blu-ray, some media players and streamers, and various retailers; but is so dysfunctional that I can't actually summarize exactly what the hell it is? No? I can't imagine why.
Amazon, though, while they don't lead the pack, knows how to get the job done well enough (their Kindle e-readers and 'FireOS' tablets all have at least adequate industrial design and build quality, and 'FireOS' is arguably nicer than some Google-blessed-but-vendor-skinned versions of Android, despite being a hostile fork; and their media-streamer hardware and software are both more or less painless). You don't necessarily go to them for the premium gear; but they are definitely good enough that they don't actively sabotage the appeal of the low prices.
3. Logistics. I don't know how they do it(if I did, I'd probably be a whole hell of a lot wealthier); but when they decide to sell something, they know how to make it impressively cheap compared to the competition, whether it be books or VM time.