You do realize that only steps 1 to 5 are necessary to take in payments? If that's the scale you're on, you're done. Step 5 is the only one with code, and I didn't count but it looks like 7 to me without comments.
Of course, if you require integration on your backend, you must write code. I don't understand what you're expecting. Stripe can't modify your code base to receive payment confirmation for you. That's just not possible lol.
I think your explanation did help to make this more understandable, that was useful. In the end (long before writing this comment) I got it to work the 'hard way' so at this point I'm set.
The problem isn't really me, since after all I got Stripe to work.
The problem isn't truly the inexperienced solo junior dev who gets stuck either - I don't imagine that costs them very much business.
The real problem is Shopify, and how potential Stripe customers get bounced off of Stripe to Shopify.
I honestly wonder how much of Shopify's growth can be attributed to "couldn't get Stripe to work, gave up." Or, to go deeper into that, the business owner who's looking for a payment solution, and wants it to be easy.
I think Shopify blew up partly because lots of other solutions were like "we can't make it that easy, but here's this 'easy' solution...' whereas Shopify was the company that said, "here's what you asked for, the easy solution - done."
I think if Stripe's documentation and solutions were better, some of the business that went into Shopify's column, would go into Stripe. Possibly a very significant amount.
Regardless "where did it go wrong?". Well, nowhere. If you think its wrong now, it was wrong always. There was never a point where stripe could magically write your backend integration with it. The 7 lines always referred to client side integration, enough code that a customer could give you money.
Shopify isn't in the same niche as stripe. I don't know if the deal changed, but Shopify payments was built on stripe. It uses stripe under the hood.
Shopify is not a payment handler, it handles making an online shop.
https://stripe.com/docs/payments/checkout/client
tl;dr, click on the stripe website a bunch, then copy and paste the generated html+js (which includes your api key, so you, the user don't have to mess with that) into your own website.
The demo UX is here:
If it's harder than that: I expect them to devote engineers and brainpower to the problem until it's not. They should solve it - that's their business.
I tried just now searching for 7 line checkout code, finding the code for it. (It's fine if it's 12, that's not the sticking point - but I can't find 12 either). It's not there.
The simplest result is this one.
https://stripe.com/docs/payments/checkout/accept-a-payment
Note the "client and server flowchart" diagram, with its 6 boxes.
https://github.com/stripe-samples/checkout-one-time-payments...
I think the closest to 'simple install' I can get is this code, which was not easily discoverable, in my opinion.
https://github.com/stripe-samples/checkout-one-time-payments...
It stand by what I said: it's a hell of a lot harder than 7 lines of code. I find the claim irritating because the reality is it's blatantly untrue.