Most airports, even terrorist fearing and gun ridden US of A ones don't behave like this. You can park outside the terminal to drop people off. It's Airport 1.01.
The British take ripping off a captive market seriously.
Also one of the indicators that free market competition between airports doesn't always help the consumer. Airports do not seek to use customer friendly behaviours to differentiate market positioning if another revenue stream can be created and more money milked off the consumer.
The Islamists must be laughing their heads off.....we keep allowing the terrorists to change our way of life AND the penalise outselves some more. Much of this is just group-think.