Emojis are standardized exactly the same way as text is, both are defined by the unicode standard. They might not be rendered uniformly, the same way that text rendering depends on the font.

There doesn’t seem to be any data that they based this conclusion on, but I certainly find it somewhat plausible. High turnover and a disconnect between employer and employee may drive the lack of reporting and enforcement you point out. It may also reduce the perceived risk, like your colleagues finding out you are a creep, or being fired.