As several have pointed out, microwave ovens last quite well if you dont use them much! Our first one, a National, was used for everything, making tea and coffee, sterilising dishcloths, (yes, Open Mike)and we hardly used the cooker. One year out of warranty it died. THEN it was explained to us that the magnetron has an expected life, much as a light-bulb does. That cooker cost about four weeks pay. Nowadays a cheapie costs about one days pay.

The obvious way to use them is for reheating previously cooked food, and precooking barbeque bangers and things that need browning later.

It isnt really sensible to use use microwaves for tea and coffee or as a main cooker, because when the magnetron is gone it is not worth repairing. Landfill. Say 3-4 years of heavy use.
I shouldn't think it is significant where the cooker was made, but where the magnetron was made might be important.