I raised three children, owned a home, drove 2 cars, took vacations, smoked cigarettes, drank booze and beer, had a dog, had a cat, dressed O.K., ate with the best of them, went out occasionally, and had a bank account.....and never made 30,000.
and always had a tax liability....paid it too!!!
Much depends on where you live in the US. For example, in parts of Florida, $25k would be very good income and a family could live pretty well. In NYC, $25k wouldn’t even be enough to live on if a single person was living in a rent controlled broom closet.
So the feds average it out. On average around the US, a single breadwinner family with two kids can barely scrape by, but if they have to pay income tax, they need financial support. So it’s just cheaper not to tax them in the first place.