There are a lot of jerk employers out there who make it difficult for their employees, independent of the laws. I am pretty sure there are "freedom loving" bosses in tiny companies who would fire their employees for "other reasons not related to your vaccination day off" if they found out. For many, good luck fighting that. Many don't have the time or money to deal with it. A quiet sick day or two if necessary will do the job on the QT. It's unfortunate that some need to do so, but that is reality for some.