[twoodfin]

What you're describing is a defined-contribution pension plan (like a 401(k) or an IRA) rather than a defined-benefit pension plan.

As I understand it, public employee unions have not been big fans of defined-contribution, preferring the more generous promises. That is a risk that both the union and the government take together.

[eru]

You can still make it a defined-benefit plan. A defined benefit plan should be easy for the government to budget for---the benefits to be paid out are very easy to forecast. (And in essence equivalent to a bond, or perhaps annuity.)

[twoodfin]

"Budget" is the operative word there: Controlling the expenditure of tax dollars is one of the fundamental things elected officials do in a democracy. Thus current governments can't ever truly bind future ones.

Unless the money is in an account with your name on it, what you have is a political promise, not a contractual obligation or an asset.