> companies don't collude to suppress salariesIf companies treat employees as commodities, which is largely the case, they don't have to collude to suppress salaries. The basic economics of commodities is enough.
The only way for employees to really have any bargaining power is to not be commodities; but trying to do that as employees is swimming against a strong economic current, because companies who can't treat their employees as commodities are in a more precarious business position than companies that can.
In other words, if you really think you're being underpaid as an employee compared to the value you create, your best option is to stop being an employee and become an owner of a company. And as an owner, if you are going to have any employees, you are going to end up under strong business pressure to treat them as commodities, so if you don't want to do that, your best option is to not have any employees in the first place: the owners either do the work themselves or outsource it to the owners of other companies with contracts.