Last I heard, Google, Facebook, Yahoo, Adobe, and a huge slew of smaller tech companies (if you want to stay in the same industry as Apple) had all colluded together to suppress wages.
I have a hard time believing anyone who claims this was an exception to a rule. It seems far more likely to believe it is the rule.
They lobbied for things like H-1B visas that let them get cheap people with limited options for career movement. You get the benefit of on-shore workers under tighter control and suppression of wages.
They colluded to influence labor standards over many years to declare broad swaths of overtime eligible employees as "exempt".
Apple and those tech giants got caught doing more direct collusion and unethical behavior. That isn't an unknown or shocking revelation. Pretty sure the mall bagel place I worked in tossed resumes from several other eateries.
I would say it happens, and collusion is not a good free market practice, and I disagree with it. Are the 'lower' salaries lower than related industries or worker tiers? Did the tech bubble generate over-average salaries, and now the big tech companies can't get tech workers to work for less? I worked at a law firm years ago, where they brought in some Russian programmers on visas for less money, but still the salary was better than what other workers in the same firm were making. The Russian workers also had a more disciplined software development background than the other American workers at the firm, were more productive and incited vicious, misplaced anti-Russian sentiment. I also remember when word processors were making a fortune in the 80s, but that quickly got watered down when more people learned MS Word and to touch type.