They don't cook food in a microwave, though. They reheat it.

The food have been cooked in industrial ovens in the factory.

Sort of, although there's importance nuance. One would be surprised how often microwaves get used in proper commercial kitchens, as in places making their own food & not reheating stuff from a central commissary. But it's not being used in the way one likely pictures when they hear this. An example is that microwaves are great for par cooking vegetables, especially potatoes.