Luton has never been able to even coming close to cracking the issues surrounding traffic queues with all of its different drop off zones that we have seen over the last 15 years.
The airport could not use just parking bays of a car park rather than drop off lanes. We have all been stuck in queuing traffic in car parks where some idiot just sits there waiting for someone to leave a space when there are plenty of spaces further on.
Then there is the issue of getting passengers across the road. The 2 lifts take 95% of passengers from the short term car park to the bridge with 5% using the stairs. Those lifts cope well with the demand but maybe 15-20 times more passengers use the drop off zone than the short term are park.
What will be needed is a gentle slope subway or extra wide bridge as lifts and stairs will not be an option due to passenger volumes. The better option subway would mean yet again digging up another section of the approach road.