I still don't understand. Surely almost every professional has a pension, but few people are in unions.
Mainly pensions are available for state employees, or union members. And for that matter, state employees tend to be part of a union.
Unions are responsible for pensions, and the only people who have held onto them as the 401k has taken over.
Edit: Because I apparently can't reply to chriseaton below - 401k is defined contribution, you contribute $x which is a set amount and non-taxable. Pension is defined benefit; you receive $x, guaranteed, after x,y,z parameters are met (age, years experience, etc). They are not even slightly the same thing. Not even close.
From https://en.wikipedia.org/wiki/Pension:
"A pension is a fund into which a sum of money is added during an employee's employment years and from which payments are drawn to support the person's retirement from work in the form of periodic payments. A pension may be a "defined benefit plan", where a fixed sum is paid regularly to a person, or a "defined contribution plan", under which a fixed sum is invested that then becomes available at retirement age.
The common use of the term pension is to describe the payments a person receives upon retirement, usually under pre-determined legal or contractual terms. A recipient of a retirement pension is known as a pensioner or retiree."
A 401k is a savings account, not a contractual obligation, so that's why it's not a pension in common usage.
The difference between a pension and 401(k) type plan is that pension is a defined benefit plan and 401(k) type plan is a defined contribution plan.
Which 401(k) plans are you thinking of require paying out to a retired employee if that employee has contributed 0%?
If you plan to spend it when you're retired then it's a pension!
Then I guess my savings account is a pension too as well as the jar of small change I keep on the kitchen counter.
This is significant because the risk is on the employer to make up any short falls if the pension fund is not able to pay $Y because of market performance or underfunding. A 401K shifts the risk to the employee. If it's not enough to provide $Y per year, that's the former employee's problem to deal with.
Companies used to have things like this - when my dad retired he had several pensions from multiple companies that worked like this. Nowadays government usually uses them to put off paying the full cost of employees.
Currently most of non-union ( and mostly non-government union ) employees have a defined contribution plan. A worker contributes a specific amount every year, a company matches some amount of workers' contribution. At the retirement worker's draw down is limited to the amount in that account. If the account did well. the maximum amount is that can be drawn is large and if it has not done well, it is not large.