From a customers point of view, if I were to take my $60K truck into a shop to have some work done on it, you can bet I will want to see some certification plaques on the walls.

On a different note, I work as an industrial electrician and have had to train employees in the past. The guys that come out of a pre-apprenticeship class definitely have a far better understanding of what is going on, and I would take a person with that experience every time over someone who didn't.