"Mayonnaise" is one of those words in English that are so hard to spell because they come from French originally. When someone wanted to say a thing was very classy, they gave it a French name. And Folks, when mayonnaise was first invented, it was a rare and wonderful thing.
Think about it: an egg-rich condiment which goes with so many other flavors in loving harmony, suddenly available even to people who do not have particularly good refrigeration, as long as they keep it reasonably cool and use it up relatively quickly once they've opened it. So it was early on realized that it was an excellent thing to put up in jars, and here we are. It is very stable while it is still in the jar as long as it does not get too terrible extremes of cold; you will ruin its texture if you freeze it. But as I say, a natural for the canning process which is, after all, pretty old technology in essence. Mason jars have been around for a long, long time.
Opening: just arm yourself with a small section of thin and relatively flexible, but sturdy, rubber with a textured surface. It will add enough grip to yours that your normal arm strength should give you little trouble. If not, what are hungry young sons [grandsons?] for, if they want you to make them sandwiches and salads, eh? Self-interest will enlist their aid easily enough, I think.