> Why don’t they speak up to their employer who can then raise it with Google?

That's not how incentives are aligned. The employer is incentivized to provide Google a service at maximum value with minimum cost and inconvenience. When an employee at a contracting agency complains, the easiest solution to the problem is to take them off the contract.

When I said tip of the iceberg... Now consider how those incentives work when the issue is harassment.