Well Parker hasn't been a regular for years, and when he was, Carrick was not considered 'comfortably better' than him. It isn't only Redcafe's views of predominantly United fans that counts. Parker was voted player of the year, and if I'm not mistaken, Carrick was out of favour and out of the team for quite a period then.
Also, believe it or not, many people outside the caf (myself not included) actually felt Barry was better than Carrick. He gets a lot of stick on here, but I reckon his 'unsung/unnoticed' work represents the exact hypocrisy of those who believe Carrick to be underrated, largely based on his unnoticed work. When Barry was leaving Villa and involved in a tug of war between Liverpool and City, the consensus in the country was not that Carrick was much better than him. Of course, most of us round these parts thought that, and naturally, we will think everyone else is crazy for not thinking so. That said, Carrick clearly wasn't better than Barry by enough of a margin for it to be un-contestable. Barry would not have been picked for England ahead of Lampard or Gerrard because there was no debate there.
Again, I'd like to re-iterate that I am a fan of Carrick, and personally think he is better than Barry, and he has also had an outstanding season (for the most part). I also have a good memory, and am fully aware the Carrick of this season has not been the same level of performance he has consistently given over the years. People are not mad, if that were the case, everyone wouldn't just decide he is great all of a sudden although he has been doing the same thing for 7 years.
He, himself, has a lot to do with the fact that he has not received the credit he gets now for a longer period. Every season he has generally had a few outstanding months and a few terrible ones. The same people speaking of the injustice were lamenting him during these terrible months. If you search the history of his threads over the past 7 years on here, it would be clear to you, even in the eyes of his own fans, that he hasn't always been that good. I mean the current thread on him in the MU forum started off talking about him being very shit for a while, and of course, ended with him being the best in the world! (exaggeration)