Honestly? Most employees just sign the damn thing. Including me, with the caveat that I posted in the above comment. It's easier than dealing with redlining a contract. 'patio11, below, seems to do something similar.
Sure, I understand that.
This is why I favour regulation/legislation to protect employees who don't understand or won't be aware of the implications. As with consumer protection legislation, you often have a substantial imbalance in power between an employer and an employee, starting with the fact that the employer is usually the one writing the first cut of the employment contract and it often gets treated like a standard form contract in practice. I think it is therefore reasonable to limit the amount of sneaky things that are enforceable if they're included in the small print on page 74.
This is also why I recommend everyone in our industry (and most others) to have any proposed employment contract reviewed by an actual lawyer before agreeing to it.
Not to discount your experience, but I actually just had this happen. I wound up walking away from an otherwise nice offer because they weren't willing to budge on their "we own everything you do, inside or outside of work" clause.
So while it may be rare, it does happen.
It's a shame, though - I think I would have had a lot of fun working there and believe I would have made good contributions to the team. I'm disappointed, but I consider it their loss. Oh well.