Interesting - it's part of the routine childhood schedule in the US but not in the UK. From NHS: "Why isn't the chickenpox vaccination part of the routine childhood immunisation schedule?"
Paraphrased: Herd immunity created by most people getting the chicken pox vaccine would make it less likely for people who did not get the vaccine to get chicken pox early in life, leaving them susceptible to contracting it later in life.
It sounds like those people should also get vaccinated, rather than not requiring anyone to be vaccinated.
I wonder if part of the reason why chickenpox vaccine is not part of the childhood vaccination program in the UK is because in the US we have for profit pharmaceutical companies who are not liable for ANY injury they cause who are paying a lot of money to lobbyists.