> Is there some code of conduct for public companies but not private ones?

There's a pattern of behavior, to be sure. The primary control on public companies is shareholder scrutiny. Gutting your company for short term gains, is not always popular. The more diverse the shareholder cohort, the less popular it tends to be.

Private companies don't mind it when they can literally start a new company with the assets from the old without the pesky plebian investors.

Ofc you know this.