> If the problem is a lack of information about global network conditions, then you can deploy canary machines around the world to gather that information.
You'd need to put machines in every single city and every single ISP in the world continuously testing every website in the world.
Doesn't make any sense at all. That's not how networks work.
If you're in Jakarta trying to access a certain website, if that website is available at the local CDN might make a bigger difference than which ISP or even which plan you're using.
You could have a 1Gbps fiber connection from your ISP in Jakarta. If you're trying to access a website in Singapore the your ISP's international link is congested, that 1Gbps will be useless.
OTOH, if you have a 10Mbps connection, and you're trying to access a website replicated at an Akamai CDN in your ISP's network, it will be way faster.
Correction: Google can't predict the speed of a random webpage to a random user around the world.
But you can reasonably predict that pages hosted at widely available CDNs around the world will load faster on average than pages not available.