FR did a head count when we came back from Easter...They noted a passenger was missing, but other pax explained he/she was not coming on board.
Again - I am sure Jet2 do head counts, no matter the mode of boarding..
You can be sure all you like, but until today Jet2's policy was to only do head counts when boarding via steps. When boarding via an Airbridge, it was accepted that the checks through the gate were suitable enough. Thomson operate a similar policy.