Charges for drop off / pick up at airports are not wholly due to the LCC phenomenon. Airports (in the UK at least) are being "encouraged" to reduce their environmantal impact, both landside and airside. As a result, they are trying to encourage the use of public transport to and from the airport, rather than large numbers of individual car trips. This applies for both passengers and staff.
I was involved in the work on ground access at East Midlands 3-4 yars ago. Charging for cars has increased, partly due to taxi drivers using the short stay car park for meal breaks, but also due to the reasons stated above. If you look at the increase in public transport provision, both in terms of locations served and the operational times of the services, to the airport over the past 5 years, you can see the quid pro quo. And speaking to former colleagues, use of these services is increasing dramatically.
If you really object to the charge at Birmingham, drop your friends at the railway station and they can get the "Skytrain" free link to the airport - similarly pick up from there coming back.
MD