> Why wouldn't an HR person or hiring staffer immediately out the company or even sue them?
They wouldn't out the company because hurting the company for no private gain doesn't help them, and they wouldn't sue the company because they’d be a beneficiary, not an injured party, and so would have no damages to claim.
And also because both acts would destroy their future employability in the field.
What do you mean? Why wouldn't an HR sue his own employer? Because binding arbitration and the employer will make sure to destroy the reputation of that HR.
We can answer that question by rephrasing, "why haven't HR employees sued their employers, time and time again?" then if it interests you personally pursue precedents.
Or better yet "Why dont employees commit career suicide for relatively minor offences that dont affect them personally and inflict no direct harm?"