Why? Simply because these traps--as stupid and disgusting and dangerous as they may be--do not instill terror.
I don't think anyone can honestly say that he is terrified about this situation. I suspect none of us will stop visiting the pines due to this situation. (Nor do the acts have any large scale impact, nor are the acts clearly designed to achieve any political objective--two components of what we normally consider acts of terrorism).
I can honestly say that the idea of being decapitated while riding my motorcycle (completely legally) is terrifying. No, I will not stop visting the pines because of it but I am alot more cautious. I think the traps are designed to punish people for using motorized vehicles on public lands and to discourage people (out of fear) from using motorized vehicles on public land which sounds like someones political agenda being taken to extreme and criminal measures. If this isn't terrorism, what is?
Jeff