While that’s generally true, the inputs and outputs and execution environment that you can count on is well-documented on AWS Lambda. That means that recreation of execution environment for the function in question is pretty reasonable locally (why is this not a thing then Amazon?!?). For the rest of AWS, you can either get credentials in place for access or mock those out somehow, but that’s not officially supported either.

I feel like the service is leaving a bunch of easy work on the table that would let people have a local development process that mirrors the remote development reality.