We did even better. When we lived in New Hampshire (and before that, upstate NY), DH would volunteer as a ski patroller. Although he was unpaid, the position included free ski passes, free rentals, and free lessons for the entire family. Every Sunday, he would take the kids--I don't ski, but I would either go with, when we had little ones, or do a mid-day run (resort was 10 minutes away), to pick up any tired/bored kids. By the time we left NH, my oldest was a ski instructor and #2 was a lift attendant, both paid positions. Kid #3 was too young for paid work, but she would pitch in--sweeping off the deck, checking lift tickets--and they would "pay" her in chicken fingers and hot cocoa. Because my kids really benefitted, I insisted that they pitch in to help when and where they could. If the ski patrol was running drills--taking someone down the mountain, lift evacuation, etc.--it would be my kids!
As to the original question--I believe that anyone can save a little money, if they put their minds to it. It just has to be a priority. I graduated college with more loans than anyone else I knew, but still managed to put 3% in a 401k. There are several factors at work--from people preferring to consume (who doesn't?), to not understanding the value of compounding, to not giving much thought to the future. These are not strictly issues with the poor or middle class--how many people that appear to be rich are just living high?
As to what age you should start Social Security--there are many factors that go into this. If you're 62 and desperate, being told to wait until you're 70 isn't helpful. Similarly, waiting until 70 only makes sense if you have a reasonable belief that you'll live a long time--when you die, the payments stop, period. It might make more sense to take SS at 62 and bank it (assuming you have the means to support yourself), rather than waiting. I don't think there's one good answer for everyone.
The other thing that's not mentioned is pensions. I know they're rarer than they once were, but some people still have them. Whether a pension system is solvent can be an issue.