Some repair guys do too and I find it really annoying when they are secretive over things.

When I worked in a repair shop if a customer asked I would let them know exactly what I'm doing.

Manufacturers don't even really want mechanics fixing them. Yes, we put that part that we know breaks in a position that requires disassembling half the engine. We'll say it's a 1 hour job. Good luck getting paid grease monkeys- now everyone shut up and buy more cars.