I suspect the problem is not with on-site equipment shortages. Both Fox and CBS contract with National Mobile Television for at least some games; I've seen their trucks at a number of games.
A big part of the problem is likely downstream. Might be a lack of satellite bandwidth, encoders, or broadcast facility equipment.
Even so, this is still very bad form. CBS leads prime-time in HD (or at least has), and wants to be a leader in sports. But without the HD component, they can't be the leader in sports. I've owned my first HDTV for 6 years now. Time for CBS to catch up.
I am perplexed as to why CBS can't do more than 5 HD games a week. Heck, the Big Ten Network has committed to broadcasting 5 HD games a week and they have not even started broadcasting yet.