My guess is that most of these jobs actually exist, in the sense that if a stellar candidate were to present theirselves, the organization would find a way to hire them.
I worked at a company where managers would endlessly push this argument to open a job posting. Of course there was no budget to hire, but they would delude themselves that the perfect candidate was out there and they'd 'be able to make a case' for the budget with the stellar application in hand. Of course they had no idea what that actually entailed otherwise they would do it in advance. To HR's credit at that company their policy was never to advertise a post unless the budget was signed off. They would patiently explain this each time some deluded optimist showed up at their door. I can easily believe in companies where the rules are less explicit that the delusion would manifest as an endless procession of advertised postings that could never be actually hired because there is no money to fund them.