Google is not a broadband provider in this context.
This is simply reflecting the reality, that different network connections have different costs and different performance. It costs Google more to transfer it over their own network than to deliver it to another network near your server, and the same in reverse, accepting traffic for your server only from nearby networks saves costs, and they pass the cost savings to you.
The problem with "network neutrality" is that the network was never neutral. Using a different connection that is shorter, or otherwise has less latency, and is less congested provides better performance, but that's rarely been exposed to end users. In Europe, it used to be common for customers to pay a different rate for EU traffic and out of region traffic, due to cost of transatlantic bandwidth, but I think that's mostly fallen out of favor as global bandwidth increased.
This is simply reflecting the reality, that different network connections have different costs and different performance. It costs Google more to transfer it over their own network than to deliver it to another network near your server, and the same in reverse, accepting traffic for your server only from nearby networks saves costs, and they pass the cost savings to you.
The problem with "network neutrality" is that the network was never neutral. Using a different connection that is shorter, or otherwise has less latency, and is less congested provides better performance, but that's rarely been exposed to end users. In Europe, it used to be common for customers to pay a different rate for EU traffic and out of region traffic, due to cost of transatlantic bandwidth, but I think that's mostly fallen out of favor as global bandwidth increased.