Ask HN: Why do we put up with such restrictive IP contracts?

I've been a professional software developer for only 5 years. However I've found that 2 of my employers, one being in the Forbes Top 10 Largest American Companies, have a clause in their employment contract stating anything planned, developed or created during the employment period (including outside of work, not using the employers tools) is the property of the employers.

I've read about this a lot over the years, have continued to work on side projects and develop things in my own time. However I'd be wary of the legal battle I'd find myself in if I ever succeeded.

I'm not in the US, and I know in many parts of the world this clause isn't enforceable. But it's always in the back of my mind when I release or begin new projects.

Why do we put up with these clauses?

I felt like I haven't fought against this because I've wanted these jobs. But it seems so nefarious, and considered "business as usual" to everyone. It feels so wrong.