Large corporations have been proven to fix wages for tech workers[1]. There's literally no way that you could have any possible way of bargaining your way around that as a single person.
[1]: https://www.npr.org/sections/thetwo-way/2014/04/24/306592297...
Actually you do, by walking across the street and getting a big fat raise to join a different company. That is one of many reasons engineers by and large don't feel a need to have someone else bargain for them - they negotiate with their feet.
You couldn't walk across the street, because the company across the street agreed not to hire employees from the other company across the street.
The free market isn't always free.
https://en.wikipedia.org/wiki/High-Tech_Employee_Antitrust_L...
And that’s just the ones they had enough evidence against.