Quite simple, until proven otherwise people of certain ethnicities will get special treatment, not because they are all terrorists, but because all terrorists so far have been one of them. Maybe that will encourage peole from those parts of the world to clean their own house.
(Emphasis added.)
Richard Reid, the shoe bomber, was Arabic?
No, nor was he originally a Muslim.
Neither was
John Walker Lindh, the infamous "American Taliban".
The "parts of the world" were the UK for Reid and here in the USA for Lindh.
(As an aside, both were convicted in federal criminal court, although by guilty pleas rather than trials, and are serving sentences in federal prisons.)
I agree that any attention paid to one-way cash tickets is utterly useless for catching terrorists.