They're kinda right. Not totally, but they have a point.
I get the feeling that this bicycle was not properly test-ridden after assembly. Any mechanic and shop worth their salt has a mandatory test-ride policy. You do it to TEST the bike to find any issues or errors in the assembly and final adjustment. They failed on two counts: to catch the loose brake lever and then to catch it during the test ride. That's QA/QC 101 in bicycle retail.
PS You're also making an assumption here: that the mechanic never touched the brake levers during assembly. It's very possible the mechanic DID loosen the brake lever and simply forgot to tighten it. Preferred brake lever position varies from person to person and shop to shop. (Aside: a middle school coach moved my kid's brake levers after I SET THEM UP PROPERLY. Annoyed me for him to be so arrogant.) The shop may indeed prefer a certain brake lever position that's different from how it comes from the factory. Another variable to add to the discussion.
This is why shops have, in addition the mandatory test rides, another golden rule: All the way on, or all the way off!
You NEVER leave something loose to answer the phone, take a break, or help a customer. You either TIGHTEN it properly, or remove it before you walk away. Failure to do this can injure or kill. Good shops follow this rule without exception.
Last edited by LV2TNDM; 08-11-23 at 12:38 AM.