Although I agree its better to be safe than sorry, most professional detailers will disagree about pressure washing. I have personally pressure washed at least a few thousand engine bays in my life, and can count just a few times in which the motor had a hard time starting afterwards. None of the problems were serious.
I know what your thinking.
It only takes one problem $$$ !!!
One was a 25 rear old Mercedes Benz, and I had to dry out the distributer cap with compresssed air. I have also had the engine fault come up a few times on the w201 3.2 liter Mercedes Benz motor from 1996-2000. In all cases, the check engine light needed to be reset by the dealership.
Regardless, I understand your point, and I always explain the chances of an electrical problem whenever water is placed on/near electrical components.