'They are herded like cattle, shouted at by those marshalling the queues, [and boy are there queues]. Then they are treated like criminals by most of the immigration officers on the interview desks.'
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I've news for you. The same thing happens to visitors coming into London. I've been there, done that.

Except for the part about being treated like criminals. But then, I don't believe that, anyway.

Keep in mind that people who have just landed are tired, cranky and sleep-deprived. They have been bombarded by airliner noise for hours with not a moment's respite. (Noise raises blood pressure.) Try to calm yourself and not let little things bug you.

I always wear hearing protection on flights, and I recommend it to everyone.

Also, it is not the fault of the Immigration Service that airplanes land at about the same time of the morning and thus people come in batches that turn into queues.