Most of these restrictions have been introduced as a result of the attack by driving a vehicle into the terminal building a few years ago at Glasgow. Clearly from Ian’s post it is not confined to the UK airports.
I have no sympathy for those that wait to collect someone in a clearly marked drop off or set down section and then play the victim when they are confronted.
Pick up restrictions and the use of car parks are a pain and time consuming, but the cost is lower than the fine. The reality is that if it is abused everyone will end up in a car park