I think you could build such an API, but there will be so many gotchyas with each special form of payment, it will be really difficult to use well. Knowing which fields to populate for a given form of payments starts getting more complicated, and dealing with the odd side-effects of each also start to multiply.

I think the processors out there (Adyen, Stripe, Worldpay, dLocal and others) do as well as they can given the ecosystem.