Don't usf have defense hills (forgot their name) that cost 125mp, 60muni to add .50 cal and if you put rear echelon you get free nades)?
Defensive positions. Yes. They do have them. However, USF, being munitions starved due to 120 MP N times for AI that is still weaker against the LMG unless you somehow manage to charge in, taking 0 dmg; And an offensive faction at that, they are quite useless. The only real usage is using them on extra lane-y maps. However, with the flame nades from Volks, and a plethora of indirects. It will be a MP/muni sink in the end. When I started playing COH2, I'd use them more regularly. Mainly because in COH1 the bunkers were quite useful, so it kinda stuck. Little did I know that COH2 USF is the most micro heavy faction and building static encampments is a waste. Same goes for UKF, but their whole playstyle is wrapped around the static emplacements. Since they are static and cost a lot, they need to be OP, but if they are OP, then 90% of playerbase will be angry because it's extremely hard to counter things that do not move an inch. God knows how angry axis players would be at elves from WC3 with their walking buildings.
I've seen some plays involving the defensive position and nades... but it's mostly memes. Average damage per minute is probably less than 80.
After building them for 30 minutes, and using them constantly. That 45th constructed position with RE in them, will launch some random nade that will kill a full HP squad and you'll have a "Worth it" moment.