Disable rel=canonical for tag archives and categories

That’s a slightly invalid question.

Canonical tag is for sorting out duplicate content in cases where you would not like to use a redirect. Also these are not duplicate pages – a tag page looks different and has different content to the “other page” you speak of.

But yeah I guess if your tag page does look exactly like the tagged page I can see your point. Perhaps a manual override would be a smart choice here.