For centuries humanity has worked to make things easier. Automation, steam power, electricity, robotics... things that made things take less time to supposedly give you more free time... There was once a dream where americans only had to work a few hours a week to earn a living wage... where everything that needed to be done was done. Of course that isn't entirely practical, there are still many fields where it takes long hours and hard work... but most of these are in the intellectual fields now.
But the pay didn't scale. The upper few in a company reaped the benefits of that easy work, getting more for less. Buying stock in a company no longer meant giving money to a company so they could improve and receiving compensation... now it just becomes a money mill, chewing away at the assets the company makes.
So people still need to work 10-12 hours at minimum wage to get by... but arn't even given that oportunity since automation has made them vanish.
We are in a transition period, a very painful one... many jobs are drying up because they have become obsolete, but our society is still based around the concept of having these man hours. You are less of a person if you do not work 8+ hours a day. You are a "leech"... But corporations are taking advantage of that by turning purely to part time employment where they can get away with it without passing on the benefits.