After seeing multiple days of massive AD groups hitting both EP and DC, it appears that the population indicators are broken. 100+ AD were hitting only 20 of us (with less than 30 DC reporting in zone chat total - we were also camped in pretty good, so not too many could've been out int he world), and the EP said the same thing with them having roughly 40 on the server at the same time, but were seeing even more AD than we were (they weren't totally camped and had pushed out), but the server showed 1 bar for everyone.

How could this be? I thought there were limits on how many one faction could outnumber the others.

The only way I can explain this is that possibly the "teleport to player" function is not counting towards population count for the purposes of the caps and indicator. If you enter Cyrodiil by "Enter Campaign" you typically have to wait a few seconds to get the invite, and a few more after accepting. Using teleport, it is always instant.