The USA should not discriminate against single people when it comes to taxes.
Even after the EXTRA exemptions one gets from being married and possibly the exemptions from having children the amount a single person is taxed is unfair.
Using standard deductions in 2011, a single person making 60K paid $8,756 in federal taxes while a married couple only paid $5,304 and a married couple w/two kids only paid $2,194.