I haven't showed a tree at the PBA show yet, but two thoughts on why people might not be showing trees:
1. I thought that maybe people shied away in prior years because names were listed on the tree cards. That practice seems to have stopped, but I would not want to show any trees if that was the case.
2. Is the Arboretum lending out stands for the exhibited trees? I thought I heard that they used to but now no longer do so. While I'd like to show a tree some day, frankly I'm not going to go out and spend the high price to buy a stand just to exhibit a tree for three days. It's too bad, as the Arboretum has tons of stands that are in storage.