That is a great example! Abstraction is most useful when it captures the way several things are more-specific versions of a more general thing. At that point it

That is a great example! Abstraction is most useful when it captures the way several things are more-specific versions of a more general thing. At that point it's not just about the functionality: it communicates to the reader. Anyone coming in can now easily answer the question, "what kinds of payments exist?"