What I find interesting, is that when I was working line maintenance at Gatwick in the late 1970s early 1980s, it was normal that a certifying engineer/technician (as a minimum, qualified to sign the pre-flight/departure check) would be on the headset for departure. When all the servicing vehicles were away, and all doors closed, I would do a last action walk around and panel "thump" check. Then I would be on the headset to clear the pushback and engine start. This was standard procedure.
Even on aircraft with a Flight Engineer, the the last eyeballs on the aircraft were the certifying Eng/Tech before the aircraft pushed back.
I think I am glad I do not work line maintenance in this 'advanced' day and age.