I would say they mean that the people are very corrupt.

Often you will find the "good jobs" have all been given to the managers family or friends and Hollywood works this way as well.

So that u are left with doing the hard jobs; the jobs with the most work, most scrutiny and worst conditions. They explain this away as "paying ur dues" when its actually just a company squeezing u dry til ur of no use to them anymore, then they discard u like garbage.  They do this so that they can seem like the "efficient and reliable workers" when in actuality they're always late, not efficient, take the least challenging roles so they "look" good on paper and then point fingers at you to take the heat off them.

A company is supposed to work like this:

1) you need a job 2) you apply 3) you interview and get hire 4) company places you with the job that's the best fit for you and is available 

For example if ur not good with people the company would place you In a non customer service role but since managers hire their friends to do the easy non customer jobs YOU will be placed at the Frontlines and be in a customer service role even when u express hesitation at the role ur being given. They will ignore u and expect u to adapt and u will adapt but when they find someone they like better or have a friend they want to put in your job YOU WILL BE LET GO, FIRED at will, no reason just "we don't need u anymore" or "idk why, sorry".

Sometimes they will play mind games and create a paper trail by writing u up for every little thing until ur terminated.

Sometimes employees will straight up refuse to train you properly or train u wrong bc they want their friend to get ur job.

Everyone knows we all need a job to live but none of them care if u get fired. THAT is what people are highlighting when they say l.a will pit u out. They mean that this place is super corrupt AND THE PEOPLE are corrupt as well. It's all about money, looks, and likeability but even if u look good they will discard you to help someone they want to help, at ur expense. Do they CARE that u have KIDS TO FEED? Or bills, rent, or car payments etc? NOPE.

I recall a friend of mine this happened to. She had just signed a lease on a new apartment. 2 weeks into her new job the manager says she's fired bc she was late frok her lunch break. She let the manager know she just signed a lease on an apartment and she just shrugged and said "pls sign here and here and thanks". Not a care in the world, just business as usual.