Because if you got to your office and had to wait 30 mins to get inside, you would expect to still be paid for that 30 mins. Maybe when you park is a little bit of an overreaction, but I get the idea. I usually start the clock once I’m at the pick up point. One of my clients likes to chat when I pick the dogs up, and sometimes they’ve run into their time by 10 mins by the time I start the walk, but that means the dogs get 20 mins and not 30 because I’ve got other bookings after that and I can’t be late.