Because Americans are rather paranoid these days and are demanding all carriers flying into the US provided beefed up security. It is so bad here in Canada that after we go trough a full bag search at the main security area, we must undergo a second one before proceeding to the actual gate! And this isn't for an 8-hour TATL flight to the USA, it's for a one hour flight on a DASH8! Having read all this, I look forward to my experience later this month...