An employer retaliates against an employee when it takes action to punish the employee for exercising their workplace rights or for reporting a legal violation of workplace laws.
Although there are government agencies responsible for enforcing these laws, these agencies typically don’t conduct random workplace audits looking for violations. Instead, they rely on employee complaints to learn of potential violations.
Even then, enforcement agencies almost never sue employers for breaking the law. Although an agency might investigate, impose a fine, or even make a finding that an employer has likely violated the law, the employee must typically bring a lawsuit to vindicate their rights.