Married couples overall pay more.
If you had a dependent, you’d pay less than the married couple.
The tax code is too complex. If you make $25,000, and you have a roommate that makes $25,000, the two of you together will pay less in total taxes than the married couple if the one makes $50,000 and the other doesn’t work.
Our society requires married family units with children in order to continue.
That's not even a valid comparison because the federal income tax rates are based on margins. You have to compare equal incomes filing as married and filing as single. The single person gets screwed in having to pay way more taxes on the same amount of income.