That was more of a hypothetical scenario than my actual life -- I'm a researcher working in academia, so in my case, I pretty much do do all the work around wha

That was more of a hypothetical scenario than my actual life -- I'm a researcher working in academia, so in my case, I pretty much do do all the work around what I produce (my university provides support in terms of office space, administrative staff, etc., of course, but the "product" is research papers that they don't have much of a hand in). But that aside, I'm not sure you got my point. Something doesn't have to be easy to do in order for it to be illegal. There are lots of reasons why a person might not want to do this -- you mention several of them. But that also doesn't mean that the employer shouldn't have the right to prevent them from doing it if they did want to. If your employer is paying for you to figure out how to solve a particular problem, generally the employer gets ownership of that work. If you then duplicate it on your own, it's a pretty gray area as to whether the employer gets some claim over it.