Yeah, it's just that ppl can't say that it's implied that employer can monitor everything you do at work with work pc. He can only do it if he is open about it. Luring employees into false expectation of privacy and then breaking it not a legal employer tactic. And on the other hand if employer tells you he won't be monitoring your emails or phone, he may still be allowed to do so in case something related happens. So very much a gray area all around.
And in the end if you are working at work ... problem solved.