Not all pensions are well managed; some have needed bailing out from public coffers. Other companies have shuttered completely, and the lack of incoming money to the pension funds made them insolvent (again, not especially well managed).
> Welcome to PBGC! Since 1974, we’ve protected retirement security and the retirement incomes of over 33 million American workers, retirees, and their families in private sector defined benefit pension plans.
> https://www.cnbc.com/2021/03/08/covid-relief-bill-gives-86-b...
Unfortunately, it's not just the private sector pensions that have been mismanaged (or raided, as you pointed out) which are in dire straits. California, in particular, has a lot of public pension headaches that will be coming to a head (and in some cases already have):
https://www.latimes.com/projects/la-me-pension-crisis-davis-...
https://www.forbes.com/sites/adamandrzejewski/2020/05/19/why...
The hourly workers (i.e., unionized) still got 100%, which was pretty unfair.