OK (long post warning!)
Apart from the Dark Web though, I cannot think of anywhere where payment is demanded in Bitcoin, never mind accepted. I cannot use Bitcoin on Amazon or at my local Tesco for instance.
I guess I could write another of my long comprehensive posts exhaustively listing every possible current and potential future situation where bitcoin is preferable to fiat for someone in some context, but instead I'll make a general statement on why you probably can't think of any and then look at one example, using amazon which you've mentioned.
As a regular poster on a financial advice forum in a first world country, I'm guessing you earn over $30k per anum, maybe everyone posting on this thread does. That's makes us all part of the global 1%. We are the rich, relatively, and we live in a first world country that has one of the most stable (touch wood!) currencies as the legal tender, we also have access to first world financial services. So maybe it's a kind of a "let them eat cake" situation. 40% of the world don't have a bank account. I'm not saying bitcoin solves the problems of the unbanked, I'm saying that there are lots of frictions and problems out there for other people that you or I don't experience.
As an example of just one friction that bitcoin is solving, lets look at the purse.io website. This is at first glance an unusual and somewhat convoluted service. It's a middleman that matches people who want to sell amazon store credit (or a gift gard balance) for bitcoin, and people who want to pay bitcoin and receive goods from amazon. Not only that but the person paying the bitcoin can request that they receive a substantial discount - up to 33%. So it might go like this:
- I want to buy something on amazon that is 60 euro, I use purse and state I want a 33% discount and I add it to my wishlist
- Eventually someone takes me up on it, I pay them 40 euro worth of bitcoin and they pay for the item using their amazon credit and it gets delivered to me by amazon
Purse acts as the escrow, and takes a small cut too.
The site has been running for a few years now, at this point you must be asking, who the hell is using this? why would people effectively pay such a premium for bitcoin with amazon credit. How many people even have a need for this kind of service? Well I was really curious too, so I dug into it.
It turns out amazon credit is almost like its own currency and has its own little economy going on. Amazon will pay affiliates or people doing work such as their mechanical turk service in amazon credit. The purse CEO says 60% of the people using his service to acquire bitcoin are in India, followed by the Philippines and Indonesia. They are earning amazon.com credit, which they can't use directly and isn't liquid for them, effectively trading it at a significant discount for bitcoin, which they are then liquidating into local currency.
The purse CEO estimates (based on amazon financial statements and giftcard research) that amazon has $10-20 billion outstanding store credit liabilities, and issues about $1 billion new credit per year.
(NOTE: I'm not endorsing purse.io, I've never even used it, DYOR).