Ask HN: Why do parking tickets across lots of cities follow a similar # pattern?

We noticed something interesting as we were looking at parking ticket numbers.

The sequence of parking ticket numbers follows a similar pattern across lots of different cities.

We thought it was because cities shared a similar software vendor... but it looks to be more extensive than that.

Anyone have any ideas why a large number of cities have the following parking ticket sequence:

827778501 (+11) 827778512 (+11) 827778523 (+11) 827778534 (+11) 827778545 (+11) 827778556 (+11) 827778560 (+4)

...and then continues to add '11' six times, and then adds a '4', and keeps repeating.

Is there a reason for this? Is it a common sequence in other places too?