The point is that it shifts the incentives: Previously, only a few cranks would contest parking tickets—everyone else would either pay them or ignore them—so issuing them had essentially no bureaucratic cost. Now, if every citizen with a smartphone can make work for someone behind a desk at City Hall, there's a substantially greater impulse to set parking enforcement policy in a way that's fair and likely to survive scrutiny.
That's not the only incentive, unfortunately. The folks fixing tickets would like there to be more invalid tickets issued; that's how they make money. Worry about winding up with something line how Intuit (TurboTax) lobbies against the IRS making tax filing easier.
