Apparently Fremont is their oldest DC and seems to attract the lion's share of the downtime. I've had 8 linode's running in their London DC for almost 3 years now and can't remember any DC related downtime. The only hiccup I've ever experienced is a host machine having disk issues once which meant they needed to move one of my vms. From being alerted of the problem to having the vm back up and running took ~45 mins with no intervention on my part.
tbh I have no idea as the London DC has been rock solid for me. On the odd occasion I've learned of Linode DCs having problems (usually here on HN) it seems to frequently be Fermont that's mentioned.
As for alerts, maybe they only automatically create tickets and alert users when there's a problem with a vm or the host it's on. Agree with you that doing the same for DC issues would be a good idea.
