Actually you're wrong. part of the trap strategy IS to collapse in the defensive zone too. The whole point of the trap is a team conceding that they can't contain the other teams forwards (and D) talent wise - ALL over the ice. It's also used to protect a lead...but the trap strategy doesn't end when a team employing it concedes between the blue line. If that happens, they retreat back and play in front of the goalie and clog below the circles. why? because again, they don't have the speed and talent to contain the cycle, so they trap to the outside, pushing opponents along the half walls and corners.
regardless Canada wasn't trapping. A team that has 80-90% of the game 's puck possession isn't trapping