I get that until recently it was considered normal and relatively cheap, but you are literally paying someone else to make food for you.
It can’t be sustainable without exploitation of workers and/or animal welfare to have that available to the majority of people on a regular basis.
If you can only afford fast food as a luxury, to me that seems like a good thing.
It’s all in how you spend your money. Like, in his list of “luxuries” you could get basic cable so you have access to news and weather, buy a used video games console/PC, buy your video game second hand and/or wait for sales, or buy a second hand/refurbished phone.
That’s frugality and something more people need to practice. However, some people are just terrible with money because they’ve never seen it used correctly. Or who knows maybe that nice smart phone is the only luxury they allow themselves.