Well dang! For some reason, ARTHUR'S pre-empted AGAIN today, this time, for Biz Kid$...
In the age of harsh economies, lessons in money handling are viewed as more important than the adventures of cartoon animal-people - a sign of the times. I don't think the newer seasons are doing as well as one would hope, and reruns only gather so much in the ratings after a while. It doesn't help PBS tends to cycle shows around, and programs that have been running longer are usually more prone to getting shafted than something created within the last 5 years.
I don't remember when Arthur aired on the local stations back in its heyday - I'll have to see if the archives reveal anything. WPT no longer airs it, but MPTV still does - 6 AM and 3:30 PM. The 6 AM time is probably more for those who wish to record the show instead of expecting anyone to be up at that time.