I think subscriptions are complicated because the surface area of the problem is so large. The Stripe Billing APIs (the recurring revenue/subscriptions part of Stripe) have gotten very good. But the challenges involved in the average subscription implementation are a lot bigger than the challenges involved in implementing simple checkout workflows for non-recurring charges.

We wrote a blog post detailing our Stripe Billing implementation: https://www.daily.co/blog/implementing-api-billing-with-stri...