ISPs typically don't outright throttle Netflix traffic. Instead, they simply neglect to build out capacity to wherever Netflix traffic comes from. I recall one case where it was just a matter of running some more cables between two pieces of equipment in the same cabinet. And of course they'd be happy to build out that capacity if Netflix will foot the enormously inflated bill.

I don't watch Netflix, but I often have extremely poor speeds for YouTube videos at peak times on my FiOS connection. Of course Verizon says it's Google's fault for not paying for infrastructure upgrades, clearly not Verizon's responsibility to ensure I can actually get the 300Mbps they advertise.