This is spoken from a position of privilege. We, as highly skilled tech workers in a field where demand outstrips availability, with probably a solid rainy day fund accumulated, we can afford to say no to a contract because we know the next is round the corner and we know how to feed family until then.
A large chunk of the workforce does not. They depend on the paycheck, need to feed people that depend on them and in their case, the employer holds all the cards. They more or less must sign. Even if they have another option lined up, for them it’s probably the choice between bad or worse terms.
That's not what the word privilege means. Having marketable skills isn't the result of privilege, it's the result of education and work.
It's just basic supply and demand. A job that anyone can do is going to have a larger labor supply than a job that few people can do. Employer demand is also a factor. Right now truck drivers are getting very lucrative offers because demand is so high, despite the relatively low skill level. Also risk factors, especially risk of death, can drive compensation sharply higher. For example working on live natural gas pipelines or deep sea welding isn't particularly high skill, but the compensation is huge because it has a tendency to lead to death.
A large chunk of the workforce does not. They depend on the paycheck, need to feed people that depend on them and in their case, the employer holds all the cards. They more or less must sign. Even if they have another option lined up, for them it’s probably the choice between bad or worse terms.