That’s observational. Other data, like wm bonus says Horde outnumber Alliance on average, therefore incentive required for outnumbered. Our wm survey says majority of responders feel outnumbered half the time or less during gameplay.
My perception is that dual faction shard balance varies, but that’s just my observation. If I was to go round the zone and do a head count, would it actually be balanced? Possibly less unbalanced than we realize. It could be that player distribution in zone is the single biggest factor of balance perception.