Certified Techs, usually are knowledgeable, but, if the management is not on top of them, requiring then to do what is right, it means nothing. The following links are what techs use to get those plaques on the wall.
My techs had to be tested and certified in their skill area or they did not work at my Dealership. They had to pass a drug test, a credit check, a previous employer that WOULD rehire them, and either a tech school or years of experience to be considered for employment.
Car/Truck
https://www.ase.com/Home.aspx
RV
http://www.rvtechnician.com/
However, I want to disclose something that happened at my local Wmart. Took our Camry in for a rotate and balance, the hub caps had holes you could see the lug nuts, but the holes were too small to get a socket thru. The "tech" tried to get the socket thru the hole, got a smaller socket, got it thru the hole, but was too small for the lug nut. I am standing, looking over the fence watching this idiot trying to remove my tires. I call the manager over and ask him to watch his "tech". After a few minutes, he goes over and tells him to remove the hubcap. Just so happens, there is a Regional Manager from W/M there. I get to talk with him. Being retired from the car business, I tell him what I think. They get a different "tech" who actually knows what he is doing and finishes the job.
The "tech" that did not know you have to remove the hub cap, had a "plaque" in the waiting room stating he was a "certified tire tech" trained by W/M.
So, you can take the 'plaques" at face value, that means they showed up at work when the camera guy was there.
Jim