How many workers would succeed at so-restricting the people at the top of the company, in that contract? Pretty much none, right? Probably you're thinking it'd be absurd for them to even ask such a thing. Why? Because this is a matter of class, and the worker isn't of the right social class to be afforded such liberty, while others are. And the worker can't force such a clause despite that resistance. Why? Because they're by-far the weaker party in the negotiation. If these weren't true, it wouldn't seem so immediately absurd to even suggest such a thing.

Why don't people who can avoid these clauses embrace them anyway, since the justification is that the company needs and deserves your undivided attention to the greatest legally allowed degree, when they have far more power over the company and are being rewarded far more for their effort? The same reasoning applies far more to them! Because it's very undesirable to be restricted in that way, of course, so damn the company's best interests.

If it's very undesirable to be restrained by these, and the benefit to the employer is evidently not so large that it's necessary to restrict those for whom the reasoning applies 1,000x more than for some lowly peon, why do normal workers accept those clauses approximately 100% of the time they're demanded? Because they don't feel they have a choice.

"Voluntary" isn't binary.