And why do they never, well hardly ever in my experience, have even any rudimentary knowledge of a second (European) language??
Many's the time I've been through Stansted in particular and heard security staff be particularly short, in english, to our continental friends who in many cases are only travelling through their security area after visiting the UK for a holiday, spending their hard earned cash bolstering our economy. It's as though it's the passengers fault they don't have fluent Essex!
For pity's sake, almost everywhere on the continent (possibly France excepted) even railway companies employ ticket inspectors who proudly display badges denoting which foreign languages they speak - it's often english plus one other. OK ours can do the same, but the second and third languages are more likely to originate from the sub continent thatn from Europe.