In common law jurisdictions, there's a term of art in law -- "unconscionable". It's when a contract is so egregiously one-sided that no reasonable person would agree to it, and it could be ruled unenforceable.

It's not reasonable to expect an employee to build up a body of expertise in a field, and then agree to be bound never to work in that field again after leaving your current job. IANAL, but confidentiality agreements that act like lifetime noncompetes are good candidates for being found unconscionable, even absent an explicit anti-noncompete statute in your jurisdiction. (Other clauses you may rightly consider unfair, I don't know about.)

Making things worse for the companies implementing such contracts is the fact that things change so fast now that they are unable to substantially benefit from such a contract. The contract is purely a CYA move.

If you have agreed to lifetime noncompete terms, you may wish to speak to an employment attorney about how enforceable the contract actually is in your area.

Civil law jurisdictions also have protections against one-sided contracts.