Honestly, I think you're trying to oversimplify...
There's lots of reasons why the workplace is the actual issue:
- One team can have a good work-life balance while another team doing the same job does not... based on the management style.
- Work-life balance can be a temporary issue because of issues or projects.
- It can change due to culture-shifts in the organization.
- It can change due to unforeseen increased demand.
- I'm sure there are a million reasons.
There's also lots of reasons why it can be really hard to jump ship:
- A person has company-specific or industry-specific skills.
- In the US, benefits (ie, health insurance) are tied to the job, so other jobs may not provide the benefits you need.
- Location of the company might suit your lifestyle.
- If you've had a job for a while, why should you leave just because a new manager or new management has changed the culture, they might be gone soon...
- Again, there are unlimited reasons why jumping ship might be difficult.
Sure profit-maximization is known... but within that algorithm there are endless variations of how to achieve that goal, and some variations have a good work-life balance and some don't.
I'm not sure if it's helpful to tell workers that if they feel overworked they can just leave... it is honestly genuinely a full-time job to look for work sometimes. I think the better approach is to train companies to look after their most important resource in a sustainable way.
There is so much that companies can, and should, do to prevent the burn out of their employees:
Managing workload and expectations, providing clear career progression opportunities, providing support, reducing bureaucratic hurdles, etc... and then there is a bunch of other lifestyle supportive things they can do; provide childcare centers, provide educational opportunities, provide physical & mental health services, arrange deals in housing, provide transportation, etc. Of course companies are not obliged to provide these things, but there is a reason why lots of companies have, and that's because it all helps entice employees to join and retains employees by reducing burnout.