It would be hard to get away with actually decreasing wages and salaries, so they get effectively frozen against rising efficiency and inflation (which we've seen happening for the last 40 years). But soon this becomes the new ceiling, and labor costs must keep getting cut, otherwise profits don't increase (at the expected rate).
That's when we start seeing the laborer take on the costs of working: transportation, uniforms, training, etc. Did you know that car mechanics have to buy their own tools? Can you imagine developing software and having to bring your own computer and devices? Having to own the latest iPhone just to test on, because the company won't provide it but expects iOS compatibility?
This is why labor rights organizations matter. Employers are guided by a very simple algorithm, whose total application to all job markets leads to the immiseration of all people who have to work for a living. This is also why solidarity matters: when we are in a position to make demands of employers, we are morally obligated to make demands also in the name of those employees who are powerless.
First they came for the blue-collars, but I didn't care because my collar was white. Next they came for the wage workers, but I didn't care because I had a salary. When they finally came for me, there was no one else left to care.