The worse lane jumping shenanigans I've seen was at YUL. There is a Nexus lane for trusted travellers (i.e. Canadian equivalent to TSA Pre) and I would see kettles get into the lane and clog up the lane. The lane was literally unusable (i.e. faster to go through normal security). I was half tempted to jump the queue and if challenged, ask them if they have Nexus. Normally, (i.e. at other Canadian airports) there would be a CATSA agent verifying if people qualify to use the lane (i.e. do they have a Nexus card) before they could enter but no such dragon existed in YUL.

Thank goodness I'm not flying regularly out of YUL anymore!

Safe Travels,

James