From what I have seen this problem mainly occurs during the evening as most of the aircraft all arrive back for the night around the same time. During the middle of the day when the arrivals are a bit more spaced out it seems to be a bit clearer. Therefore im afraid you will probably come across it again. Since they have stopped letting you pick up/drop off from outside the terminal all it seems to have managed to cause is lots of traffic jams, but no doubt has made the airport a nice load of £££ from people exceeding their free 10 minutes.
The light timing to get into the airport off the by-pass is a joke and needs to be changed as it stays red far far too long. I have also on several occasions been following someone into the airport and then they decide to stop in front of you on the round about in the area where it is painted in big letters NO WAITING
. The airport should really have someone there monitoring this and moving people on asap. Another popular trick is driving along and then just before you get to the crossing between the drop off and the path to the terminal people will just stop their car and decide to unload their bags and passengers there, completely blocking the road. Didn't they read that the first 10 minutes are FREE. Especially as they are dropping off so won't be hanging about waiting for someone. With regards to the car park situation its is bit of everything really. There is a lack of space in the drop off not helped by usually been full of lots of taxis waiting for people. This could be solved by at least letting all the taxis pick up from outside the terminal. The drop off area could also do with been bigger but then that would mean less spaces in the carpark and then less £££ which we all know is king. Also this is probably all not helped by the introduction of more flights and airlines resulting in more passengers to pick up. Finally the last situation you mention with regards to people finding out they have over stayed the 10 minutes and having to rush back to pay for tickets, and not having enough change and having the machine eat your card etc. This could be solved by making it say 20-30 minutes free. But again in this day and age where airports are no longer interested in looking after the passenger and more interested in extracting as much ££ from you instead, don't expect the 10 mins to increase any time soon. A good idea which I have seen at a couple of US airports is that they actually have a small car park off the airport where you can park for free and wait, then when your friend is outside the airport you can simply drive up and they are there and ready to go. Gets around people waiting on slip roads. Maybe a use for the old parking area near the old terminal??
Finally my last rant at the airport would be, BUY A NEW BUS. The number of times I see whilst sitting on the flight deck people getting completely soaked when it rains having to run from the long stay car park whilst juggling bags, baby, pull along bag etc. If they are not going to buy a new bus, at least build a covered walk way as far as the car park. There's a reason why there is a lot of green grass in NI.
P.s is maybe BFS helped in the fact that they have the long road leading up to the airport where you can park at the side and wait without having to block up the roads on the airport, where as at BHD the only place where you can sort of do the same thing is at the old entry point to the airport need the train station. Therefore we end up with the mess you have described.