> I wonder if that would run into net neutrality-type issues
It absolutely would. Who is Apple or anyone on HN to tell one developer that their app is more important/costly/uses higher priority SDKs than another?
Well, maybe app binary sizes are an objective metric. Apple could even raise the existing cap and give Uber a bit more room to breathe, while charging them for the inevitable expansion of their app.
I think the analogy would be more equivalent to AWS. There are different costs associated with using the various SDKs (i.e. Lightsail, EC2, S3, SageMaker).
I'd also say the more it can be defined in terms of technical reasons the better.
There are R&D costs to maintaining a cutting edge, industry leading 3D Graphics SDK for iOS that the primary users beneficiaries of said library (i.e. Epic, Xbox) should contribute to.
This would require a bit of mindshift and context.