I think any policy made on assumptions is poor policy. There are employers that offer unlimited sick days. How could that be if people always take the maximum amount of time off? We know people feel compelled to come to work while ill. Absenteeism is hard to measure and quantify, and if it is being driven by factors like environmental hazards or actual medical illness then simply restricting paid leave is unlikely to fix the productivity problem and may actually make it worse.

So, good policy should show a) how many days off people get b) how many they actually take c) how many can be shown to be due to medical issues (seriously ill people will seek medical attention, even in America, and that can be quantified). If these basic data are lacking, then the policy has about as much a chance of succeeding as throwing darts in the dark.