The one thing missing from that calculation... the rent goes up over the 30 year period while the mortgage is fixed (subject to changes in tax rate and insurance as value hopefully increases).

9 years into my current home and my 20 year mortgage is substantially less than renting a similar house in the same subdivision. And because it's 20 year, the interest rate is lower, and when I retire, I'll only have to cover tax and insurance at a fraction of the future rent.

Exactly. After 8 years there is absolutely no way I could rent a comparable house in my area for what my mortgage costs.