As a 22-year veteran cameraman and member of 2 ( formerly 3 ) unions, allow me to gently set you right.
First of all, Craft Services is frequently the backbone of a crew’s endurance, so shall we wag a civil tongue? You dig working 18 hours a day, 6 days a week in the bitter cold…with no food? I thought not.
A film crew, like an army, marches on its belly.
In the 1950’s into 1960’s, the so-called Studio System was collapsing. The Unions were very strong but nothing could force the Studios to keep full-time employees on staff. As the decade of the 1960’s progressed, more and more film technicians had two things happening. ( I say technicians, but truly I mean below the line as well as Directors, Producers and Writers ). The studios were letting go of staff technicians, writers, producers and directors. The other thing was that Unions were negotiating for screen credits ( partially as a result of thing one ).
The increase in credits is directly due to union negotiations. The above the line personnel get to negotiate credit before the picture. Some main below the line jobs are credited before the picture, and then typically run fully afterwards. It’s not typical practice, it’s negotiated for and hard won. Not for nothing, but I sit and watch credits. I have my whole life.
Making movies is blisteringly hard work. It’s also the best job in the world, to me. Those people get their due. You chose to sit and watch or not after the movie ends, fine- but I feel it’s only proper that they get their credits.
Interesting true story, not Urban Legend. Written in great detail by Julia Phillips in You’ll Never Eat Lunch In This Town Again. Julia and Michael Phillips produced The Sting. Julia was the first woman to win the Academy Award for Producing Best Picture. She was told to negotiate for same size font for her screen credit.
Nobody told her to negotiate for the THICKNESS of said font. Yep. Her name is the same height as her (ex)husband’s, but the letters spelling her name are wafer thin, barely legible…live and learn.
Cartooniverse, IBEW 1212, NABET 16 and formerly IATSE 600. 
( First time someone sent me an email showing that my name hit on IMDB for Credits, I laughed and laughed. Cool !!! )