Here's what puzzles me. I have looked into Stripe, and just browsed the Adyen webpage. Both of those services seem to require you to maintain your own "active" server that can run server side code. PayPal seems to be unique in being able to take payments from a passive web page, because the customer conducts their transaction at PP's website. This is why I continue to use PP for my tiny little business (without eBay)…
i agree it's actually kind of bad that payment providers don't provide this page. todays technology could even render it on the webpage of the customer shop without redirecting fully to another page (scrpt scr=paymentproviderscript.bla? or so?). If people have to maintain and host their own script it makes them horrible prone to attack. In which case i'd rather have a payment provider who needs to secure it than ever…
They can't do this because then the untrusted merchant has access to everything again. It needs to be sandboxed in a separate page so that the customer is talking directly with the processor, with SOP, cors, https, and simply not being able to intercept PII and payment information.