Why Do Parking Enforcement have Sirens?

Have you ever wondered this? I have EVERY DAY.
One day in particular i was parked on the wrong side on street cleaning day reading an art magazine, (no matter why i was in such an odd reading area), when parking enforcement pulled up. This old blackberry (with sweet juice) walked over to my car and with a rather crude manner said "You caint park here! why would you be he anyway iss twelve o' clock," the point of this is that there was no siren. She cant chase me, because i wasn't moving. As soon as she stopped blowing steam into my car i pulled off. So whats the need? do they get in to high speed parked car chases often? What does a parking enforcement siren sound like? maybe a its sounds like a fruit truck..
Or maybe its just there to make them seem to reek with authoritah? I'm just not sure....

-RAAD