Doesn't Netflix have cache boxes hooked directly into the ISP networks?

I'm sure Netflix uses a lot of AWS, but as a percentage of their total traffic (which is absolutely enormous), it's probably not that much.

Yes. And although much of what Netflix does is in-house, it’s done the math and realized that for some of its workloads, AWS is just better. Especially when looking at all of the areas where Netflix is available and needs datacenters and in some of the specific compute options Netflix needs. It’s not serving traffic through AWS. It’s using AWS for storage and compute.

It also certainly doesn't pay by the public price book.