We do. It's called social security. Technically, it should be enough to pay the bare minimum of your needs upon retirement, if you're in a low cost-of-living area. It does not ensure a comfortable retirement, and we have enough problems in our government to erode our trust in getting the full payout from the system.

It's also "100%" paid out if you wait until 67, or 75% at 62. Also, I note you said "employers must pay"; we pay social security as a deduction from our paychecks in the form of a 6.2% tax. Employers also match that.