I've done a fair amount of retail at Lowe's Home Improvement, and again at Wal-Mart. It's not a great job but it's one of the few in a small city that can work around being a student.
With that said:
RE: older people working to support themselves because they have no savings or other expenses - Yes absolutely this happens. I didn't see it as much at Lowe's, mostly because that place has fewer opportunities for, well I don't know how to say this politely, for the decrepit. You don't have to be capable of lifting 50 pounds for EVERY job but there's just so many you can't do unless you're relatively hale and hearty.
We did have some older employees there, but more on that in a moment.
Now at Wal-Mart, where you can a greeter, be a register jockey or just fold and hand garments or fabric all day, there are a lot more possibilities. You do have to be able to stand on your feet on that absolutely unrelenting concrete floor for hours on end though. Seriously I've done much rougher work than Wal-Mart, but Wal-Mart made my feet hurt worse and gave me larger calluses on my heels and toes than any other job I've ever had. I can't imagine how it feels when all the cartilage in your knees is gone.
Generally they were people who just never saved, who never had anything, who were paying for the lifestyles of a child or grand child, etc. It was sad. They were usually good employees, but there just wasn't a lot Wal-Mart could offer them because nearly all of them were only capable of short shifts. At least they were willing to hire them. People talk about of bad about Wal-Mart but I know for a fact my store kept its fair share of elderly people in much better living conditions than otherwise.
I didn't see anyone older than 60 working there for giggles. We did have a few people who just worked there to have a job, but they tended to be younger retirees or stay at home spouses. They're usually some of your best employees because they're happy outside of Wal-Mart and the prospect that "This is my life and all I will ever have" doesn't occur to them.
There are a few happy career Wal-Mart employees, they are the backbone of that company and it treats them like garbage.
I can't bitch completely about how Walmart treated me; I got screwed a couple of times but overall it was okay. I started at $8.90 an hour and quit 2 years later, with $11.00 an hour pay, full time hours, health insurance, 401k, etc. I call that fair, considering I made it clear I was out as soon as I found my chance.
Now Lowe's was a different story. Because Lowe's is a bit more specialized and has some areas of the store where you might find some things people are passionate about, you do find some "pleasure" workers, including some old ones.
We had one woman who worked in the garden center was in her 80s, but she loved to grow flowers and shrubs. She was one of our best employees, she knew how to make things grow and how to plant them.
There was an older man, about 70, who I wouldn't mind imitating. He worked part time in Tool World, and his job just kicked all sorts of ass. All he did was talk about tools all day, and he got to play with the newest things. He would take his earnings, go buy materials and tools on his employee discount, and go home and just make random stuff.
His whole job was stock tools, organize tools, talk to people about tools, talk about his projects... and because he didn't depend on the job for anything other than supporting his hobby he was always happy at work.
There's another job at Lowe's that's even better. Assembler. All you do is put together wagons, furniture, lawn mowers, grills, etc. That's it, all day. Literally that's all you do. You get your own little area, you get to shoot the breeze, no one bothers you as long as you get it done, etc.
But if there's one job I learned that's worth doing in your old age, it's watering in a nursery. You get up in the morning when it's calm, before it gets really hot, and you just water. It's peaceful.
So I guess the short version is, yes there are some older people who tragically keep working at advanced ages. A few of them are just working to work, many are not.
And there are some crappy jobs that are a lot of fun if you don't depend on the wages from them to live. I kind of plan on getting a bull shit job when I'm formally retired, at least for a while. I wouldn't mind working at Lowe's again if I had a place with a table saw to learn some new skills.
Hobby stores, specialty stores, etc. tend to afford a lot more of this. Like I could work at a Best Buy and find the job interesting. But a soulless generic retailer sucks.
Though Wal-mart wouldn't be so bad if it were a regular store and not a supercenter I think, and it would be worlds better if you didn't really need the money.