My wife and I make okay money in a middle class area, but, due to a combination of good luck, and contrived to circumstances, we recently got to watch a college football game in the stadium’s super executive corporate sponsor level suite. It was awesome. Open bar, amazing catered food, and people networking all around me who are clearly in the c-suite of their respective companies. I had a list of crazy things I was going to say if someone asked me what I did, but it never came up.
In most countries you are taxed note the more you earn, so two people earning 60k is MORE than 1 person earning 120k.
Taxes are paid in brackets and having two independent incomes makes each one fill their own lower bracket before going for the upper ones.
It does make a difference, in Spain for example nowadays even married couples fill taxes separately because it’s just not worth it tax wise to join incomes.
US actually pretty much doubles the brackets when filed as a married couple. They did this awhile back for that exact reason were filing seperately often made more sense. Now it makes way more sense to file married if single income and is sorta a wash if both make the same amount.