[seibelj]

The government guarantees them. Banks would never offer this product otherwise.

[cortesoft]

The government does not guarantee mortgages.

[chordalkeyboard]

it is more complicated than the gp makes it seem, but 30 year mortgages are absolutely a creation of policy in the form of federally owned corporations that rebuy mortgages that were written according to a standard policy.

https://www.grarate.com/article/history-30-year-mortgage