More people have a 401k today than ever had a private pension. While a pension does have advantages (and not everybody has a useful amount in their 401k), your odds of having a good retirement plan are higher today than ever.
That still leaves a lot of people with a terrible retirement plan though. SS is something, but that is about all you can say about it.
Come - the median retirement age 401k balance is $97k. This isn’t useful, and most people get a 401k default enrollment without contributions so account existence isn’t a useful metric. Your odds aren’t better if you don’t contribute.
I’d also note you have to be at a company that even offers a 401k. Only 45% of Americans have access to a 401k, or have their own IRA. This isn’t a safety net - I’d like to see you do a high wire with only 45% of the area of your walk covered with a net, and of that the median segment doesn’t have the strength to hold your weight. It’s a political gambit to fool people into voting against their best interests.
You miss one other point - when pensions where common they were not backed by guarantees. I had some [distant relative] who worked for a company with a pension for many years, just before he was ready to retire the company went bankrupt - the company pension was invested in company stock which meant the pension was also bankrupt. A few other incidences like this and the US government started backing pensions - but they also put in strict rules that made them a poor investment in general. A 401k is better because you can get good investments while also getting enough diversity for investments.
That still leaves a lot of people with a terrible retirement plan though. SS is something, but that is about all you can say about it.