"I completely don't understand why they are searching passengers going from Canada to Canada."

And WHY are we carrying PASSPORTS to travel within Canada?

You need 2 pieces of picture ID to get on a plane from
point A to B --
That means a DRIVERS LICENSE (if you have one...) and a P.P.
Bullshit.

Get used to the phrase "PAPERS PLEASE!" folks.
We are quickly moving towards a fascist-like state
not-unlike Nazi Germany where we need "papers" to
go anywhere by air or sea within our own borders.