It seems your expecting Blender’s Python API to behave in a way that it currently doesn’t.
Abstracting over element types, multiple meshes etc - and exposing the selection.
What your suggesting could be written as an API ontop of direct data access, although it probably needs to be integrated into operators for it to be useful.
So the answer to your question is - either access selection directly, or write your own utility functions.
While I’m interested in how the Python API could work differently, this probably requires changes at multiple levels.
I’d rather look at this in terms of problem/solution, showing code for current behavior and psudo-code for how it could work differently.
Although I don’t personally have a lot of time for this, it’s the kind of thing that could be prototyped in Python.