It’s sufficient to say there is an immediate profit motive to just fire the workers and pocket the surplus, I think.

That doesn’t explain why they don’t just do a three day work week and pay workers 1/2 of what they did before. Cost wise it would be the same and would make the same profit as firing half the workforce, but you’ll almost never see companies reduce hours instead of head count.

They don’t reduce hours because that means the person will probably get a second job. Now they’re not the sole employer and the only thing keeping that person from poverty. This makes getting fired a smaller threat as the second job can hold you over for longer. It also gives the employees more bargaining power when negotiating for raises / benefits as they can threaten to quit and just live off the second job for a bit, they can also play both employers off one another to compete for the employees time. These all increase worker power which capitalists/employers don’t like.

A long unemployment line has the opposite effect and decreases worker power. It makes firing a bigger threat as the employee knows it will be harder to get a job, so the employer can work them more and pay them less. It also reduces employee bargaining power as the threat of quitting isn’t as real and the employer knows it.

This is why a Marxist approach is needed, economics just looks at the dollar and cents, but if you look only at that you can miss underlying power dynamics that also drive behavior.