This is the lowest of low-hanging fruit.
My guess is that some Amazon warehouses were doing it, but not all. This news seems to be about rolling out an Amazon-wide policy, but the headline makes it seem like there were no measures prior to this (which AFAIK is false).
Who needs sick time should able to take it and it should be paid time off; Amazon workers are not well off people, they live paycheck to paycheck. By taking sick leave would leave them without a rent check, Some of them would think twice, some would just come to work sick. And why don't they do something like an incentive program for workers? To give protective equipment to their workers, give a bonus for working during the pandemic and charge more for shipping if needed. Yes we will be charged more, we would buy less but the numbers would balance out. And knowing those workers are human to, I wouldnt mind paying more for shipping just to mitigate their impasse.