Because workers are a local resource like any other. Businesses don't get to just "use" them with impunity.
Your answer makes no sense. You say workers are a local resource, I agree. You then go on to say a company cannot “use” them with impunity. What does that mean? You appear to be saying\ the co. cannot exist without the workers, true enough to a point but the workers have no jobs without the company(s). You can make the point workers can leave a company but then so can a company leave the workers as we are seeing here.
Until such time as we allow slavery in the workplace, i.e. a sort of indentured servitude, it is not possible for a company to “use a worker with impunity” as you put it.
I believe what is lost on many people is the reason for business. There is but ONE reason to start up a business, that is to make money. I never heard of an individual with money who decided to start a business just to employ the good people in the area. Sure the relationship between owner and worker are symbiotic but make no mistake the very seed that starts the business tree growing is the cash of the owner/investor. As the saying goes, a poor man never created a job.
The business owners today are governed by enough rules and regulations to make the Unions wholly unnecessary. They exist due to the laziness of workers and the greed of people who can use the lack of intelligence of the worker to hijack part of their check to line their own pockets. No one who has a decent work ethic needs to fear being fired unless economics dictates a workforce reduction. A business adds and sheds workers based on it’s need to survive and grow, it’s called the “market”.
Nobody should ever be guaranteed a job. When that happens we wind up getting what the automobile companies got and we see what happened to them.