If you think about it, it's a bit odd that there are so few mercenaries in this day and age. When you look back on history then from what I can tell, mercenaries were much more common.
Unfortunately professional armies fail the one test that matters these days, which is the number of opportunities they provide for private actors to siphon money into their own pockets. So we have decided to ignore the lessons of history, because private profit today is worth social collapse tomorrow.
It won't stop everyone, but done correctly it could stem the most egregious of revolving doors.
I think it's very likely that entities like drug cartels already pay for things like location data for DEA agent's cellphones.
It was new information to me but supports your idea.
[0]: I'm not saying we shouldn't have a welfare state, it's clearly necessary in the modern world, but the America of today is nothing like the America that was intended, for better or for worse.
I think the whole idea of the US being the world's most powerful country and acting outside our borders would have been something the founders would have struggled with, because they fought a war to get away from the world's most powerful country.
And a permanent, standing, large, and fairly dysfunctional (look at descriptions of military leadership and its civilian oversight in WWII and earlier, then look at same in Vietnam, then look at the linked Afghanistan Papers documents in this thread re: same in Iraq and Afghanistan) US military is even newer, only 80ish years. Even more recent if you consider its modern form to have taken shape only after the Vietnam draft ended.
I wonder if the civil war counts here.