calibration

[kon]

I have a friend that always ask me (with joke)
 Why always we need to calibrate every electronic device ?
If anybody here has an answer for this I will glad to know (The answer  can be like a joke but I want  also to know also the real answer)
Thanks

[Soeren]

Hi,

Why always we need to calibrate every electronic device ?

Well, closed loop devices are self adjusting and components like eg. a transistor are all electronic devices and you don't calibrate them, so perhaps you need to be more precise.

[kon]

Thanks Soeren,
Can you give examples of devices that use open loop control or example of device that need calibration