Ah, recruits as in officers, okay fine, sure the Academies would be volunteers. I keep forgetting that sometimes officers wear the armor (at least in theory, we never see this in the movies, but we'd never really know unless one of them took a line or took off his helmet to show us). I was thinking conscripts, since Lucas mentions "normal guys getting shanghaied" by the Empire to fill out the ranks later on. Conscripts tend to make the worst kind of troops, at least in our world.
It might be one of those sorts of deals where people volunteer in order not to get drafted though, as is eluded to in the deleted scenes for ANH (with Biggs) for example. So in a sense they're still being pressured to join up, but some jobs are better than others. The Empire is so big, chances are most soldiers aren't going to be doing much other than glorified guard duty, rather than getting shot at by Rebels or being ordered to quell uprisings, harass the populance or get choked by Darth Vader...