Iirc, different classes have different recharge ratios. (Or am I mixing it up with W:ET?)
Also, certain command posts give recharge boosts, but I think someone mentioned this already.
We learned that it's not bodytype-based lately.
And the Soldier has a resupply-ability (Scavenger).
And the Medic has an ability to recharge supplies faster.
So I guess everyone has initially the same recharge time, but can improve it through abilities.