It's only absurd if you waive a right that is beneficial to you. In the EU we have a legal right to work no more than 30-something hours (I don't recall the exact figure).
Now, I'm fine with the idea that no-one should be forced to work excessive hours. So I have no issue with a right of this type existing.
But that's different from me choosing to work particular hours. So, in my case, that right is a restriction to my freedom that has no particular benefit. So I waive it.
You shouldn't be able to waive any right preemptively. If you choose to waive the right to trial for a current case or choose to waive the right to not work over 30 hours for now, that is fine. If you can waive the right to ever go to court or permanently waive the right to not work more than 30 hours, that is a problem.
Now, I'm fine with the idea that no-one should be forced to work excessive hours. So I have no issue with a right of this type existing.
But that's different from me choosing to work particular hours. So, in my case, that right is a restriction to my freedom that has no particular benefit. So I waive it.