The drop off/pick up at Luton is £5 for 10 mins then £1 per min after that , drop off in the car parks followed by a shuttle bus ride is free for short amounts of time.
It states on their website cctv is in operation and a £95 enforcement charge (reduced to £55 if payed within 14 days) is payable for drivers dropping off on approach roads. The airport is council owned so in theory could issue parking "fines"