(Fun fact mini-thread) We found evidence that most countertop microwaves sold in the US are manufactured by just one company. Here’s why we think Midea probably made the microwave in your kitchen, your friend's kitchen, & your parent's kitchen: https://wrctr.co/3e5PjWZ 

We confirmed w/ Midea that it makes & sells Toshiba, Comfee, & Black+Decker ovens. We’re also confident that GE, Whirlpool, Breville, Insignia, & others also sell microwaves that were built & likely designed by Midea, though all parties that we contacted declined to comment.

The first clue is that at a given capacity, there are usually at least 4 dif models w/ the same wattage & dimensions. They have identical contours inside, ventilation grates w/ identical patterns, & some of them say plainly on the rear label that they’re manufactured by Midea.

Import records (which are public information) also confirm that Midea supplies microwaves to those brands.

We took the covers off some microwaves (please don’t do this at home), & the similarities were even more striking: Many use the same magnetron (the key component that creates the actual microwaves), transformer, & capacitor.

We usually found a Midea logo printed inside, too.

None of this is to say that all microwaves are truly identical.

Although the cheapest models are essentially generic ovens designed & assembled by Midea, some brands, like GE & Breville, do play a part in their microwave designs (again w/o confirming a relationship w/ Midea)

What about other microwave suppliers?

Galanz (a 30-min drive away from Midea) has a big foothold worldwide, but a small share of the US market

LG & Samsung make their own microwaves

Panasonic makes its own mid-range & high-end units, but budget models seem to be made by Midea

Even among microwaves that are intended to be identical, there can still be functional differences from unit to unit.

But for the most part, you can expect the Midea-made microwaves from many brands, of a given size & power rating, to be very similar. https://wrctr.co/2Ts6sCw 

tl;dr