One problem here in Connecticut, especially in my little corner of Connecticut. We don't have enough varsity officials to cover three person games on our busiest nights. Heck, on a few Friday nights during the season, especially during flu season, and when a few officials might be injured, we don't have enough varsity officials to cover two person games. A few weeks ago, we received an urgent email from our assigner asking us to reconsider opening up a Friday night if we had previously blocked it out.
That, and financial considerations, are the two main reasons why Connecticut is, for the most part, a two person state.