I was surprised by that too: typically I’ve only seen such high latency on Netlify based sites which exclusively uses aws-east for the whole world.
People often misconfigure things by pointing their domain to netlify's IP with an A entry, but this is a user problem, not a netlify problem.
I'm sure their builds/functions run in a single region but not static files
For the a CNAME record (e.g. wwww) it can be pointed to their CDN.
I think if you use Netlify DNS for your domain, then you can point A records to their CDN because it’s an alias at that point. Like, A record aliases on AWS Route53.