They probably did at one point. Then, a wrestling coach who allowed his own wrestlers to be molested by a team doctor came into power. He wasn’t very bright, but he found that by pulling his glasses halfway down his nose and yelling instead of using the calm speaking voice that he used in his re-election campaign commercials, he could fire up and scare his uneducated constituents. When the state wide lawmakers in his party saw how well that strategy worked, they all adopted it and convinced their own constituents that anything that the reasonable lawmakers from the other party wanted to do to keep people safe and thriving was actually a massive infringement on their freedoms and an attempt to make all of their children gay, transgender and ‘*woke’.

*they don’t actually understand what this term means, but they just know that it’s bad and will cause all of their churches to be taken over by satanic rioters shooting 5G rays at them.

I think they allow exemptions. This outbreak sounds like it's concentrated in an immigrant group and the families probably have some obstacles to getting vaccinated due to poverty, language differences, etc. A lot of times schools and daycares will do conditional admissions where they don't require the vaccine to start attending but tell the families they do need to get the vaccines as soon as possible. Sometimes "as soon as possible" doesn't end up being very soon and kids slip through the cracks.

Also, babies don't get the measles vaccine until they are 15 months or later if they are late because of illness.