It would be helpful if you provided references given you claim to have researched this issue in depth. Even using your death rate of one in 5,000, this equates to 50 deaths a year in Australia in an unvaccinated population compared to none in the latest data I could find for Australia. 50 dead children, devastated parents.
As for vaccination it creates an immune response but not as strong as if you contracted the disease. Some people get a disease twice so it is not surprising when some unvaccinated children catch it. However the severity of the disease is reduced by the vaccination.
The reality is that if all Australians followed your example we would have polio and its devastating effects back in Australia
