I know a few people who work at such companies, and they all have some sort of subscription service with a third party that handles all these parking tickets for them. If they lose, they pay the ticket, nothing else. If the company wins, they pay a percentage of what the ticket was.
To give you an idea of what type of advantage cops take over these drivers.. There are a few streets in NYC that a friend's company makes deliveries to. The cops know the delivery schedules, are make sure to be there on time, dropping off the ticket pretty much as the vehicle parks. One of the drivers confronted the ticketing cop once, only to be shrugged off with: "What do you care? You're not the one paying for it."
I'm glad to see this come as a service to the general public. There's some hope that with enough people fighting bogus tickets, someone will eventually get the message and stop handing them out so casually.