The final walk-round checks @ most UK airports are conducted by the Head set person. To get an on time 'off chocks' the tech crew must have been in the flight deck for some time. At many of the airports worldwide that I have worked on the ramp, this check even by the tech crew is condusted amongst many ground vehicles some still attached to the a/c.
Being emplyed some time ago as a safety auditor the operation and safety check levels of effectiveness are only as good as the inividual, the check is even more fraught when it is dark or the weather inclement. That said I cannot see that there is much more you can do. Someone mentioned the loss of this task as an engineering function, from my experience I doubt their imput or checks were particularly any better. It is a visual check plain and simple.