My experience is that not all Apple Genius Bar techs are ... geniuses. Take my last interaction as an example. I was trading in my iPhone 13 Pro on an iPhone 15 Pro. I have dual SIMs (eSIM + physical SIM). When you have dual SIMs, your signal bar has a horizontal line through it, where each half represents the signal for each of the SIMs. The genius informed me that this behaviour was because I had a VPN running, and he couldn't run diagnostics for the trade unless the VPN was turned off. I told him to give it a whirl anyway just to humour me. He rolled his eyes and you know what? The diagnostics worked and to his amazement.
I'm not making fun of anyone here, just musing out loud as to what formal training some of these people get?
It works the other way, too. I called Apple Support because I had inadvertently smashed the screen on my iPad Pro. Oops! They insisted that I bring it in to an Apple Store for diagnosis. Really? I complied (100 km round trip) and the genius at the Genius Bar agreed that the screen was smashed. No kidding? They didn't have one in stock (I had AppleCare+) and I asked if they could send it in for me and I could pick up the replacement when it arrrived? Nope. No can do. I was told that I'd have to open a support case with Apple and they would send me a box, and I could return the unit that way. When I got home and asked Apple Support exactly what lunacy this was, they said the geniuses at the Genius Bar were in error, and I could've left it there instead of waiting an additional few days for the box to arrive. D'oh!