It is really not hard to go to https://smartasset.com/taxes/income-taxes and try your own examples to test the claim in reply #35. For example, in New York, NY (with high state and local income taxes), $50,000 income becomes:
Single, no dependents: $37,952
Married, 4 in household: $40,941
Looks like that site does not include the child tax credit, which is dependent on whether they are under 17. So if the family had the maximum $4,000 credit for two kids under 17, then the net would be $44,941. However, if it had one in college and one under 17, the net would be $43,441. Or two in college, the net would be $41,941.
So yes, the new grad has less net at the same $50,000 income than his/her parents did earning $50,000. But the $4,009 to $7,009 advantage that the parents had is likely more than eaten up by the higher costs of a household of four rather than one.