How is it different ? From the perspective of the companies, it is in their interest for the prospective employee to bid to fill position.
"Hey there Plumber, if you do this job, I'll give you health insurance for the two days it takes you to do this job. I'll provide a gym membership, free coffee, and pay your taxes"
In the case of plumber, the benefits for plumber to take the job is they get to make money.
Your analogy might work for short term contractors but not for a full time employment, where essentially you are putting yourself at your employers service virtually 24/7 with almost no extra pay while doing intangible (aka knowledge) work where the employer might get 5x or 200x return out of your work, but essentially you will just get almost linear pay raises (even including performance bonuses).
You cannot compare a full time knowledge worker with a gig worker that does tangible physical work.
Kind of like a plumber saying "We don't need to dig up your front yard and charge 9 grand, for 500 bucks we can robotically patch the pipe from the inside".