There is no way consumer to know the quality of parts being used

In regular shops, 99% will use whatever cheapest parts they can from distributors. Even dealers may not use OE parts.

I have a friend in China, whose factory makes brake pads. He sells pads to US distributors at price of $3/pc. The distributor labels the pads and sell to parts stores. Consumers pay about $14-16/pc for the same pads.

If you really concern about the parts, you would need to order particular parts made by a particular manufacturer, like OE, etc, online. then you can diy or bring your parts to a shop and have them install 'em for you.