Remember this isn't a criminal offense. Most warehouse workers are 'judgement proof', in that they don't have the assets to pay anything. The court isn't going to say 'you have to quit your job' because it has financial interest in NOT paying for their welfware because they can't work at what they're skilled at due to the non-compete.
Amazon would pay more than they could recover pretty much every day the court trial went on. Also, there might actually be enough push-back if they tried to change laws.
Personally, I'd like to see a law of 'sure, write up whatever non-competes you want. However, it means that the the employee is still your employee during the non-compete period. Which means you still have to pay them their salary and benefits'. Don't want them working for the competitor for 12 months? You gotta pay them to sit on their ass for 12 months.
Finally, it sounds like they stuck the non-compete into their boilerplate employment documents. It's not intentionally targeting warehouse people, though I suppose that with the increasing amounts of robotics in them, it might be deliberate, so said workers don't go describing how the robots work.