I think it's a case of both affiliate preference and money. Here in Louisville, our NBC affiliate carried virtually every NBC game in the 80's, even pre-empting whatever 10 am sitcom the network aired for the noon show (Just Men, Hot Potato, Super Password, etc.). They also had most of the syndicated game offerings as well (Kennedy TPIR, $1M COAL).
OTOH, our CBS affil. (now ABC) never picked up any games from syndication, and never aired Beat The Clock, Whew!, Child's Play, Tattletales, Body Language, Press Your Luck (save for the last couple of weeks in '85), and cleared Pyramid starting in fall '84, but they did air TPIR, however. They usually aired B/W sitcom reruns in the 10:30 slot, more than likely for monetary reasons, but finally cleared the slot when Card Sharks premiered.
Tyshaun