They do play somewhat of a role, but... again, for someone pulling in $72k - even as a single person, they may be paying ~20% of their income in taxes. Assume $12k for insurance - maybe another 18% - this might be approximately 40%.

Married and with kids might increase health insurance, but would reduce taxes because of deductions.

Locality - local/state taxes might increase this - I'm in a mid-level tax state - not no taxes, but not a New York.

Someone earning $72k who is married would have a $24k deduction - they'd be paying taxes on max $48k. MFJ status with no kids earning $72k would be < $6k in federal taxes.

Single earner at $72k - federal income tax in US is ~$8900. It's not nothing but that's nowhere near 50%.