Nothing is being discriminated or artificially slowed down. You pay to use their private network. Standard tier means you leave their private network and move onto the public internet, which would be more open to ISP net neutrality issues if anything.
You are aware that the Internet is a collection of different companies running different networks, right? Google's network that is serving public traffic is part of the Internet. The inter-network routing decisions that are made are literally the crux of the net neutrality arguments made so far.
Yes, networks comprise the internet, but it's not free to run on any of them. Some are better than others and cost more.
As a typical consumer, this negotiation is out of your hands with ISPs balancing performance and profit (although tilted towards the latter) but as a Google Cloud customer, you now have some control over how much of their network you use - all the way to the edge or just regional - without any discrimination of the traffic itself.
