As noted in another thread, we volunteer at a food bank locally. It’s highly regulated and inspected. We have it on good authority that we can tell recipients not to worry about short-date or out-of-date canned foods for at least two years, if they store it at reasonable temperatures. The only exception is when dents are deep enough on the sides to cause a fairly sharp edge or point in the dent (possible tiny cracks in the metal), or if the dent is along the seams at the top (or occasionally bottom) of the can. If that seal breaks due to a dent, it may or may not show leakage, but can become a problem.
My only real concern with older cans is that previously there was far more leaching of unwanted substances, due to older manufacturing techniques. But the more modern cans don’t even have a seam on the bottom, and are sometimes even lined. Lead leaching is of far less concern these days than in decades past. Personally, I doubt I’d be eating those century old oysters, though. LOL!
We use homeopathic remedies a good bit in our family. Though not food, I learned something from a company I deal with (a smaller homeopathic lab that sells both to professionals and over-the-counter retail stores). They put no expiration dates on their remedies (the only one I know of). I talked with the senior person at the company, and was assured that they are neither required to, nor do they need to put an expiration date on their products. The person said some of their very old remedies we have (an older formula we like but they no longer make) is perfectly fine today if reasonably stored. She said that other companies use expiration dates primarily for marketing purposes – they want us to throw out “expired” remedies and go to the store and buy more of their products. I suspect we’re looking at the same thing with much of the canned food as well – it sells more products. (And with foods, it’s also the food companies’ attempts at further reducing litigation by trying to force older stocks out of peoples’ homes – and wastefully into the trash.)
We’ve chosen to keep (and use/rotate) much more freeze dried and dehydrated foods in the past few years, and of course the nutritional value of particularly the freeze dried stuff is reportedly much better long term. Plus, contamination over time (leaching from cans) is not an issue with the vacuum packed stuff compared to store-bought canned foods. But I certainly wouldn’t throw out a can of beans or carrots simply because it “expired” six months ago. If a regulated food bank can get away with up to two year out of date canned goods, you KNOW there isn’t a major problem with food safety.