It's not blind trust. i go to work knowing that the peolple who carry out most jobs on the ramp are trained to do that job. If I undertook responsibility to oversee every operation from maintenance actions to deicing with everything else inbetween the aircraft would never get off the ground.
I think they call it workload management.
There is an element of risk getting into a metal tube and getting airborne then getting it back on the ground. There is SMS in place to look at all the risks involved and mitigate them as best as possible whilst still managing to perform commercially in all sorts of weathers etc.