Though these jobs are not truly "recession-proof," they have a continual demand for workers, thereby increasing the chances that one who has the skills will be likely to find employment.
[1][2] What makes a job so-called recession-proof is society's perpetual need and heavy demand for the service related jobs.
Certain fields, such as health care, education, law enforcement, and various computer-related occupations are thereby always in demand.
But as to which specific jobs are the most recession-proof, this varies in different eras, as the times change, and each recession differs.
When a recession occurs, many people, especially those who have lost their jobs, those whose jobs have been threatened, or those who fear losing their jobs are motivated to seek education to be able to obtain recession-proof employment in their future.