Makes sense - I guess it's just an unclear emphasis on their offering which essentially is taking that work off your hands. What would you prefer to see?

A checklist of cases that I might not thought of. I would group example code around different use case and not around API endpoints.

For example Braintree is good in that sense: https://developers.braintreepayments.com/guides/recurring-bi...

I know it's not a payment gateway's responsibility, but some further handholding on tax and VAT, invoicing issues would be handy.

Agreed. It's much more like "just handle these 50 edge cases and you're good to go."