Good to know. Is it enforced rigorously within Amazon? Specifically the attention and effort aspect. Do Amazon employees really have to get written permission from Amazon to work on side projects that might make money?
Bearing in mind that amazon has a reputation as a shitty employer, I personally would make desired revisions to the contract, hand it back to them and say "this is what I want, let's negotiate".
If they insist on the boilerplate version of the contract, and cannot be persuaded to alter even small details to make you more comfortable, then you should nope the fuck out of there (unless you have no other financial option, in which case take it and immediately start searching for a bullying-free workplace. Don't forget to tell them on the way out why you chose to bail).
I do that all the time.
Where I come from, there are plenty of standard clauses put in every contracts, which are 100% guaranteed illegal and not enforceable.
Usually, ignoring them is easier than negotiating the contract.
You're mistaken. If the other party to the contract doesn't believe you, they may enforce the clause anyway, and then you'll have to pay for a lawyer to go and get it unenforced.
Particularly if the clause was related to something time sensitive (e.g. something to do with shares, or something that prevented you from launching a product at the right moment), the court will not reward you for the opportunity value lost.
If the clause is not legal, you should address that /before signing/ and have it removed from the contract. Doing otherwise on the assumption that the clause is unenforceable is arrogant and puts way too much faith in your local judicial system. It probably won't bite you in the arse, but it's one of those "if you do shoot yourself in the foot, you're gonna blow your whole damn leg off, not just the foot" situations.
I'm talking of minor things. Like the classic non compete "You can't work in <x> domain for 1 year after you leave <company>". It's illegal and invalid at the place I was when I signed that contract (safe advice: don't generalize). Every one knows it's not valid.
If the company wants to enforce it, they also have to take lawyers and risk their reputations. Then it will go to trial, where the judge will pick up the exact same case for 10 years ago that defined 1) that clause is invalid 2) company loose the trial and can't appeal 3) exact figures for damages and payback.
You'll find many such cases online regarding Amazon.