Doesn't auto mode also auto-accept code changes? Assuming their data is good, I'd be fine trying an auto mode for permission prompts (as the article says, I do eventually get prompt fatigue and stop examining them too deeply). But I absolutely don't want it changing code without my permission.

It will indeed change code. It will also happily do stuff like write into your user's SSH config and leave you with permanently broken SSH until you find and fix it.

Most users of coding agents do want the agent to edit their code, and don't want to have to click something before every edit. If you want something different, that's why it's a setting.