Being immune from lawsuits might have something to do with local liability laws. Imagine, every child gets vaccinated and the local population has a love for litigation, as a manufacturer I would not like to spend my profits on lawyers; court cases etc. I would choose to leave the business of developing/manufacturing vaccines and go into the foot cream business (lower risk, higher reward). In the end when almost every private company but one has left price of a vaccine might be equal to a new Lexus. The other option would be for the government to start manufacturing vaccines but I believe this is the ultimate nightmare for a certain group of people...