Actually, banned in is used in certain situations. For example this book is banned in India. That political party is banned in Egypt. This movie was banned in sweden. That means that the book or political party or movie is not allowed to be shown read or function in that country. A person or organization that is not allowed to enter a country is banned from that country. Example that airline is banned from flying to France because of its poor safety record.

In this instance the 'from' means 'against'. Remember some English prepositions have not explanation. One just has to learn them.