Any of the recent food star autobiographies will tell you that life in a kitchen is a 60-80 hour grind, every week, and that investing in a restaurant requires only slightly less foolish optimism than buying a boat.
It's possible there are other factors at play here, but I don't know enough about the situation to bring those up.
There are also a _lot_ of addicts, psychopaths, morons and other assorted human detritus, of ever conceivable hue competing for these jobs, which also depresses wages.
Furthermore, restaurants don't have any damn money. Restaurants are on razor thin margins always. Usually a bad week or two from going under.
Qualifications for working in the kitchen consist of:
1. will you work for very little money? 2. can you work ok when you're high and/or drunk? For fancy places: 3. can you safely handle a knife? 4. will you toil endlessly for no apparent reason?
That's pretty much it.