Uhm they can, one can buy amazon.com giftcards in any retailer in US and at any coinstar kiosk for cold cash.
Hell one can even buy amazon giftcards using bitcoin via gyft.com and receive 3% bonus back!
If anything its Paypal that is unable to reach as many people as Amazon, and continue to alienate more and more users every day by screwing around with them etc.
Oh look it Apple fanaticism is alive and well, one gets down-voted for pointing out that Apple can not be trusted with security in light of recent events
Paypal regularly close/freeze funds for customers, putting many many businesses out of business, causing all sorts of issues
This can not be done with your "quasi-bank niche", until it happens to you you dont realise how shitty Paypal can be, and if they block you altogether you are effectively cut off from being able to spend money online, well this was the case until bitcoin came along