An example to the children

One of the things I do for fun is drive a school bus for a Christian school. We only drive for special events like sports or field trips. This leads into something that Ive seen and can't understand.
Why do we Christians think it is ok to break the rules if its just a little thing? As I said I drive a bus, but I have a very hard time dropping the kids off in the "bus zone" when parents seem to think it is a good place to park " A few minutes". Signs posted say "no stopping, parking or drop off/pick up. When we are suppose to be examples to the children and we break the rules, especially in front of them, how are we to expect anything but disrespect for any rules. If we break them, why can't they? O.K. it's a pet peeve of mine and I'm just letting off steam, but I ask you, are you as guilty as I am of practicing what you/I preach?
john