The Ptolemaioi are the definition of massive bureaucracy. Economic, legal, and military. Even the klerouchoi aren't really "citizen" soldiers, though they aren't professionals either. They're reservists really, and an effective reserves system requires a good bit of oversight and organization. And in addition the klerouchoi, there were also some professional units in the Ptolemaic army, though mercenaries and klerouchoi constituted the majority of the soldiery.