Immigration Queues
Immigration control is in the hands of the UK Border Agency, and it is not within the gift of the airport, airlines or handling agents to do something about.
The government has no money (as we all know) so I would imagine that employing extra staff at backwoods airports such as BHX, which the news media hardly know the existence of, is not going to be the top of the list for spending money that we haven't got. Of course, were it to be a London airport things might be different!
We, the public, have in part made this situation, with our apparent steely opposition to joining the Schengen area (as reported ad nauseum by the Daily Mail, Telegraph and the like). In making the border nearly as hard to cross as the US border has just made the situation what it is today.
We have made our collective bed, so now we must sleep in it!