It is not exactly the same thing. The commenter you are responding to is looking to avoid overdraft, not having an insurance on overdraft.

I'd agree with the idea of avoiding overdraft entirely unless a customer signs up for it. I don't want transactions I can't afford to go through. I manage my accounts quite closely. For me such situation would be 99% an unintended transaction that I would like to cancel.

By letting such requests go through, banks put the burden on the customers to clean up after a wrong or, in many cases, illegal transaction.

YMMV.

I've used a credit union my whole adult life and they did't offer overdraft as an option.

That's because it was automatically enabled by default. This is what banks would do if they weren't predatory.

Then they charge $30 to reject the transaction, another $30 when you go "odd and try to swipe again", then extra money because you didn't have the $30 to cover the fee in your account, then recursively until you're $1200 in the hole and they're refusing to cover it.

Correct. I called my bank and had them enable this for my debit card. They made sure to clarify that ACH transactions will still go through, however.