Earlier quoted context omitted.
A 401(K) is not a pension. The latter is funded entirely by the employer.
That's not the case. Pensions are not always funded entirely by employer. In quite a few cases the salary of a worker is reduced by a certain amount that is added to what is contributed towards a pension by an employer. 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%?