That's not correct. Lots of places WILL allow transit for citizens of [most countries] if they have a valid visa to where they are connecting and many places WILL treat holders of PR cards somewhat differently including allowing transit for PR card holders (that would otherwise require a transit visa).
I read the instructions on the German airports site as saying a Canadian PR holder will be allowed to transit through the German airports - my only reservation is whether they will know that a valid PR card is, in effect, a Canadian visa.
@Bland : check with Lufthansa or Air Canada if you are travelling with either of them (esp if code share AC/LH). My experience is that both of those airlines know the rules for transiting via Frankfurt quite well - although it may take a bit of effort to find the person who can asnwer your question, the people responsible esp in Frankfurt & Munich (who make the board/no board decision) know very well what's allowed.