Stealership mechanics are trustworthy because they won’t try to sell you parts and service you don’t need.
They’re also ASE certified.
Good mechanics are paid to do the work and dishonest mechanics are paid to work for the lowest possible price.
If a shop doesn’t have respect for its mechanics skill and talent, it won’t have respect for its customers.
It isn't the mechanics you have to worry about there, it's the service advisers. Many don't know what they're doing and many more try to upsell those hugely expensive services. Unless it's warrant work, I never go to the dealer.