One of the problems that I've seen in England is that in the junior schools where most of us were first introduced to carols, many of them now use pre-recorded backing tracks of modern jazzy Christmas songs. This wouldn't be a problem if they all used the same ones, but each school has its own favourites so that there's no set canon such as we had.
I remember a wonderful evening in the college bar where we sang all night. The only things we all knew were Christmas Carols and rugby songs. We finished up singing carols all round the campus. It was October. I'm not sure such an event could happen now.