However it appears to add that tag only if I typo the name, if I follow a good Amazon link (with or without the affiliate) then it doesn't get 'corrected'.
Although since the rewrite rules are downloaded from a remote location (over HTTP, not even HTTPS!) they could in theory decide to rewrite any links in the future, without many people noticing.
While they could update the list, it's still typo correction. As implemented, the url needs to be typed in the location bar and the domain can't exist.
Edit: sorry about that last part. http://amazon.co does exist and does get corrected.
However it appears to add that tag only if I typo the name, if I follow a good Amazon link (with or without the affiliate) then it doesn't get 'corrected'.
Although since the rewrite rules are downloaded from a remote location (over HTTP, not even HTTPS!) they could in theory decide to rewrite any links in the future, without many people noticing.