Sure: Private insurance overhead is around 15% (up to 20%) while Medicare/Medicaid overhead is around 2%.

They are both insurance programs.

Aside from variations in fraud detection efforts (which Medicare/Medicaid should do more of), what justifies such a gap?

It's various methods by which they grow and retain market share, which Medicare/Medicaid don't need to do.

> Sure: Private insurance overhead is around 15% (up to 20%) while Medicare/Medicaid overhead is around 2%

This doesn't say the difference is in marketing.