Uber has over 6,000 employees, so let's say you send a survey to all of them that's confidential asking about harassing behavior. Let's say you get a number like 6% [360] feel they've been harassed. Let's say you talk to the 6%, but half of those seem ambiguous (i.e. nothing in writing, this individual has complaints about a number of people and past jobs, individual's account seems inconsistent). Perhaps other employees don't even fill out your survey because they don't trust it's anonymous, or that when investigating their claims HR will be able to know who the "troublemakers" are.

Nonetheless you take the 3% that seem solid and to find common threads (the same person being complained about, HR people failing to record/raise complaints, etc) but without everything in writing it's so hard to prove who raised a concern about what last year. Maybe many of those people already have left (voluntarily or not).

I think if we want to solve these types of problems truly, we need to think about developing auditable systems (e.g. HR gives you a signed and written copy of every complaint, which their supervisor sees, and that lying on such a complaint be a legal offense on both the individual and corporate level).