You are forgetting that the polio vaccine is the traditional vaccine which has been perfected after several decades of research. So we cannot compare it with novel mRNA technology which no one knows it s long term side effects. The same mRNA technology, pfizer uses 30 ml and Moderna uses 100ml. The antigen load is different in both. Why?

Moreover never ever in the history of vaccines was there a efficacy more than 90% for a vaccine. Do you know the loop holes in it as described in the below article?

https://sogmoe.medium.com/the-3-unanswered-as-the-big-pharma-need-to-answer-while-making-the-big-claim-of-more-than-90-2e352290668f?sk=b6655070c3a680238a2773b3ca00072e

The danger is no one knows what they are dealing with. Better safe than sorry later for unknown unknown.