If you have the ticket you can "self-checkout" by going to the machine to pay, not involving others. If you don't, you need to speak with the person who "manages" the parking lot, the person who sits in the little booth.

Some cars also have (something like) a bank/credit card attached to their front windows near the top, those people can just drive out and the payment is automatic right before the barrier that blocks the exit.

It's an easier UI. I visited a car park recently that had switched to ticketless operation, and now in order to pay, you have to enter your car license number using the on-screen keyboard. It's not exactly hard, but it's an order of magnitude harder than 'insert ticket, insert payment card'.

so they can charge you a fee for lost tickets :)

Most of them let you prepay before you leave to keep the flow of traffic moving, but I figure you could look up the fee by tag too since they already record it. lol.