I think the disconnect is characterizing the ramp area is a "service". Yes they pay to pave (maybe) and maintain it, and that's a nice "service" if nothing else is made available, but OP already mentioned he didn't want restrooms, cookies, crew cars or busty nitwits to flirt with, so the only "line service" provided by Signature was the lineman who acted as bill collector, and their existence.
This is worse since we can't just leave the plane hanging in the sky, so we're forced to go *somewhere* -- unless VNY Ground could suggest a taxiway to sit for an hour. Maybe they could have
I think the disconnect is made worse because, if I park my car somewhere with no signage, just to chill for an hour, I expect to do so freely because streets are paid for by municipalities and they generously include spots to park as part of the plan.
If I pulled over from a road and some dude came to ask me for $10, and I did NOT pass something looking like this:
... then I would probably be ticked off just like OP, and probably drive away too.
What's funny is -- the "guy asking for cash to let you park here" is pretty common in Africa. Of course, the implied threat is that they're asking for a tip to prevent vandalism to your car while it's unattended. No mention is made about whether this vandalism would be committed by this same watchman with hand extended should he get stiffed.
So maybe signature needs to offer a separate free ramp, and have goons go trash planes parked there every so often if a lineman is not tipped.