Tank Reloading Speed Logic...

When the tank reloads its primary weapon and you still have several rounds left (for instance, for the squad support landship), why does it take just as long to reload from empty as say, with 14 out of 15 rounds remaining? Shouldn't it follow a similar logic to the time it takes some infantry weapons, such as the single reloads seen on some revolvers and sniper / standard issue rifles?

I'm imagining that IRL, tank crews would individually and manually reload each shell. So, if you only fired 1 shell out of the 15 that are loaded, then the tank crew member would only have to reload 1 shell, translating to a quicker reload time than having to reload all 15.

In game, I find it brutally annoying having to fire a few times with the squad support landship and waiting for it to reload the full time as if it were empty. This is especially true when playing some of the In the Name of the Tsar maps, which only lets you choose some tanks. 

Any thoughts?