Even though I didn't work at one of the colluding companies, I got a ~20% step function in my income when the collusion finally collapsed and wages became more competitive across the industry. Considering indirect effects like this, the amounts stolen from workers in related industry probably amounted to hundreds of billions of dollars.
The theft by google and apple had effects broadly in the economy, far outside of the colluding companies.
If you hold down the wages of of the top 10% of laborers, then the next 10% have a harder time getting raises too, etc.
In addition, if those systems of collusion become established, they're a strong profit-motive to gradually expand how many workers are being harmed.
For those who don't remember this, here's Wikipedia's article on it: https://en.wikipedia.org/wiki/High-Tech_Employee_Antitrust_L...