Reason For 4 And 5 Grenadier Shipment Difference?

read this in the update, completely support: Adjusted Fortress Age military unit cards to a nominal value of 1000 resources Age of Empires III: Definitive Edition – Update 47581 – Age of Empires

but this reminded me of the many problems legacy civs have with thier cards. this approach to unifying cards around their appropriate resource value should also be applied to them.

using this as an example, what is the reason for some Civs having access to the 4 grenadier shipment, and the rest having access to the 5 grenadier shipment?

the 4 grenadier shipment has the same value of an age 2 crate despite being in age 3, yet its the largest available grenadier shipment for some Civs.

they should both be boosted to 6 grenadiers, at 1080 resources it would follow standard shipment values.

that the unit sucks and is not worth that much is a different problem.