We can get hung up on a roux or not (fwiw I have been making one of those for decades but this is the first time I've learned its name, it was always just "white sauce" in my head). But the OP has a point: cooking is a basic life skill, and as such there should be no excuse other than severe disability as to why people can't or won't do it.
The money argument doesn't sit with me. I was an immigrant student on no money back in the day - I literally came over owning one pot, two plates, one shitty kitchen knife and one wooden spoon when I first started building a life here. On a measly budget of £10/week, which even then was more than tight and had to include the weekly £1 bus fare to get to the shop (in the days of £5 for 5 peple day savers), as well as hygiene products, I had no choice but to cook from scratch.
I built up a stash of basic herbs and spices over time - you start off by buying salt, the next week pepper, the week after that a jar of mixed herbs etc. Same with cooking equipment. And yes, some stuff was very much trial and error, but you were hungry, so you ate it and knew what not to do next time.
My mother was a single mum who openly hated me; she had no time to help me learn how to cook, so I learned by watching, later by following recipes myself. No one taught us in school.
It's not the same as wiring a plug, changing oil in a car and the many other silly examples that were being given here - for starters, you don't do any of those daily, so you can get someone else to do it if necessary. Try getting someone else to cook for you daily.
It's also not always energy-dependent; there are lots of no-cook recipes, lots of things you can do with only a knife (one of my two plates ended up as my substitute chopping board until I could afford one), lots of things you can cook with only one pot on a single ring on an electric hob if you don't have a full kitchen.
It's fine if people say they don't want to learn how to cook; there are alternatives here, thankfully, even if they are bad for your health and burn a hole in your pocket financially. But don't find excuses for people, because there really are none if you're able-bodied and of reasonably sound mind.