When I was first setting up my house I was confused why they opened and tested everything. Plugging in the rice cooker, the fridge, even light bulbs... what?!
Yeah, I quickly learned you really do have to check everything. A lot of stuff just comes in broken (dropped, run over, who knows). The stuff that is is not visibly broken quite often simply does not work. I think maybe the PIs get all the factory rejects?