There are people who can (or in some cases must) opt out based on occupation. For example, see https://www.nerdwallet.com/blog/investing/teacher-retirement-sys

There are people who can (or in some cases must) opt out based on occupation. For example, see https://www.nerdwallet.com/blog/investing/teacher-retirement-system-pension-social-security-benefits-work/ https://www.nerdwallet.com/blog/investing/teacher-retirement... for a brief discussion of some of the mess.