Microwaving takes less attention and less skill, though. And less cleanup. And you don’t need to own a pan. And you don’t need to own spices (steak is a bad example ofc). And you don’t need to think about the side dishes. And you don’t need to agree on what’s for dinner. And I think it’s worth repeating, you don’t need any skill and can’t really screw it up. And you don’t need to worry about it going bad because you were too lazy to cook it. Etc.
Processed food may not be cheaper, but the flavor:effort ratio is waaaaaay higher.
Throwing a steak in a frying pan is about the same effort as a microwave frozen dinner, and is objectively cheaper.
There's no universe where processed food is cheaper.
You can microwave a meal by tossing it into the microwave and walking away, you need to actually participate in cooking a steak and then clean up several surfaces. The stake is conservatively 10x as much effort and time is money, plus microwaves use far less energy.
Processed food isn’t a single unified thing, the prices definitely overlap but the minimum and maximum prices for processed foods are lower. That’s why our food supply ended up looking like it does, economies of scale beat home cooking. That’s true even going back thousands of years where communal cooking drastically reduced the fuel needs in warm climates.