I've found that people in many areas of work are given guidance and training then either: a) forget over time b) ignore the policy because they think they know better c) ignore the policy because it is inconvenient (this is my favorite!) d) ignore the policy because it is personally advantageous to them (either for reputation, money, etc)

Reminders never hurt (assuming they are reminders and not over the top bigoted screeds)

So many people think they understand what the impacts are if they bend some of these rules, or ignore them a bit for convenience. I would argue that most of the time, unless the stakes are consistently high, they do not.

Probably employing the wrong sort of people then.

I would hypothesize that every single medium to large organization has this problem. Anecdata confirms, but that's not data, obviously.