I grew up solidly middle class and we never went out to eat besides occasional fast food if we were on a roadtrip, I wasn't even allowed to purchase school lunches. However, I had a stay at home mom that cooked everything!
Now, that I am an adult none of my friends that I would call "middle class" have a spouse that stays at home. Only those families that are very well-off have 1 adult that doesn't have to work and they tend to be rich enough that cooking most meals vs. going out doesn't matter much for them.
I think this is a case where "middle class" can mean a million different things. I don't think someone is colloquially middle class if they can't afford the crappiest house within 2 hours of their office (slight exceptions for major cities), yet others define it differently.