Low population servers got almost empty PFs.
I know it's very hard to unite all PFs even on a single datacenter and SE not likely to do it but you gotta help us somehow.

Im from Lich(EU) and recently I rolled a character on Odin(EU) just to compare populations (xivsoul says Lich got highest pop. Its bullshit). So here's example of PFs roughly at the same evening time:
ODIN: http://i.imgur.com/3IyVxXj.png (used MS Paint to glue 2 pages of pf togeather)
LICH: http://imgur.com/RjyUqBh

People on Lich stop playing because theres not much to do and as they are gone theres even less to do for the rest.