I’ve always seen these jobs as targeting people who could be retired but want something to do. Pay isn’t great, but they offer very flexible hours for straightforward work. It engages you mentally (which the older you get, the more you’ll appreciate).
That's the ideal/stated desire (and historically this was more likely to be true and it does hold true in some cases: graduate school adjuncting is more likely to be of this sort), but the economic incentives and overproduction of graduate degrees relative to the jobs requiring them have functionally made adjuncting the service class of academia.
And just because the hours are flexible doesn't mean the pay isn't an issue: Employment perks are relative and flexible hours are way more common than they used to be. For most people who qualify to be adjuncts, they could also freelance (which I do do) and get both payment and flexibility.
