Less for laws to govern the 90% to allow the driving population an easier time of it.
if someone wants to drive that metal death machine, then you need to prove you are capable. Or risk it and take the automatic jail time - like knife carrying.
Traditionally the discount for cash in many professions is due to avoiding tax.
i.e. a plumber will do a job for cheaper if they are paid in cash as they won't be declaring that work in their accounts - avoiding the ~20% tax that would be due otherwise.
Sadly I've wasted many hours of life in focus groups watching the mob navigate. Back buttons are *used prodigiously, and woe betide anyone who breaks a gesture swipe back - that one gets scowls.
It was also weird and slightly dangerous growing up in North London and not being allowed to carry a knife. Less dangerous than prison though.
*should clarify the law states it's a certain length, so Stanley knifes are ok, pocket or flicks. Non.