The definition of CC in the Powerplay manual shows it is not just about collecting money :
Also this is a universe where the local government is basically hiring private individuals to go participate in the local shootout with the gang or opposition political party, or where the local gang can ask you to go blow up the police. Local systems appear to have a large degree of autonomy as can be shown by the different government types of various systems even within a major faction. The major factions again are not like modern nation states on Earth. The Empire has major senators with effectively pocket empires of their own. The Federation can be likened to the Old Republic from Star Wars. Each system is its own mini government and micro nation, sending representatives to the big assembly on Earth but otherwise running their own affairs, and free to make its own laws or vote to leave the Federation.
Patreus collects on debt owed by local system governments. Legal debts accrued by purchasing of weapons on credit, which Patreus no doubt can provide legal documentation and proof of purchase. If you look on the old Galnet reports, there is even a system that managed to renegotiate its debt with Patreus and which did not get segments of its population having to sell themselves into Imperial slavery. That itself can be seen as an example of Patreus "expanding" into a system as he still would no doubt hold considerable leverage over the local government even with a negotiated deal. Probably aside from interest rates, there are other clauses or kickbacks beneficial to Patreus such as ownership stakes in key industries. Patreus's effect on for example Federation systems shows the imposition of new taxes. This again could be done through pressure on the local government and the local government then passing legal laws within its own jurisdiction to raise taxes, which may ultimately go towards repayment of the debt owed to Patreus. In such a case, Patreus may be literally collecting money, but on a legal debt which was genuinely racked up by the system government.
