How often do you remember when exactly you pulled in? Particularly if you are in a group at a restaurant and have a lot of other things on your mind?
Rarely, but paid parking generally takes two forms for me: ANPR* regulated or Pay and Display (the ticket). ANPR is easy because you don't display the ticket in the car; you take it with you and it has the time printed right on it. Pay and Display often doesn't give you a spare ticket but in those cases all I need do is tell Siri to start a 30 minute/1 hour/whatever timer.
*ANPR, in case you don't have it there, has a camera pointed at the entrance and exit of the car park. Your registration plate is read when you pull in, you pay at the machine and enter the registration number there, and your plate is read again when you leave. You don't need to show a ticket on the dashboard and you can add more time by phone or SMS message in most cases. There's also grace period after the plate is read at the entrance to give you time to park or to change your mind and leave.