If you follow the source trail it lists Cloudscene as the source, who seem to be some marketplace for buying and selling cloud services. I highly suspect it’s a count of the data centers they have listed by their sellers, which would bias the US and explain why there are so few for China.

If you follow the trail you get Cloudscene as a source: https://cloudscene.com/region/datacenters-in-north-america

They seem to be some cloud services marketplaces, where they link up buyers and sellers. I suspect it only lists the data centers that they have listed that are included in the graphic. That would make a lot of sense, since Chinese data centers used to service people in China are unlikely to be listed, which is why it says in all of China there are only 300 data centers.

I don’t even have gigabit and if I try to download a game from Steam, it seems to eventually catch up to the disk and has to pause while the data is being written to disk. This is to an SSD.

If I was the only person in the house I wouldn’t pay for gigabit, I’d just go for a couple hundred and that would be heaps. 100 would likely be plenty for most people too. But if you do a lot of downloading I probably wouldn’t want less than that if I had the choice.