The Real Reliability Tests

Call it "Occupational Health Psychology" problem if you like, the moment I saw the huge temperature difference between Grand Canyon National Park and Phoenix, the first question that came into my mind is "Do all my gadgets' manufacturers and their suppliers designed their reliability tests appropriately and perform these tests with conscience?". 
I hope they really do. I have to suffer the unbearable 38~40ºC in Phoenix, drive all the way to Grand Canyon National Park, and wake up the next morning in 2~6ºC for the sunrise.
Imagine if the manufacturers and their suppliers never tested their products or components in extreme environment; Worse still, imagine they do see failures and think that it is "not severe enough" or "very unlikely to fail in ambience", I am not sure if my poor little gadges can survive this +/-36 degree Celsius temperature change within 24 house.
I'll keep my fingers crossed......