It's an interesting question. I've done a little reading on the subject and the psychology behind "vaccine hesitancy" is fascinating and complex. The vaccine hesitant include people from diverse, and often antagonistic social, economic, education and political backgrounds all around the world. There is a really a lot of issues at play, include distrust of real or imagined systems of authority, a wide variety of conspiracy theories, a general hesitancy to use any medical interventions or overall suspicion of modern medicine, even simple fear of needles is even considered a significant underlying factor.
It really is fascinating... in a "watching a car crash in slow motion" kind of way. Unfortunately, doing so from inside the car rather limits the entertainment value.