Its mainly the regulations and labor. With the fires in the news maybe quality control has improved and there is less crap out there now. The cells are very common and cheap when purchased by the pallet. A good, tested and reliable battery management system is not cheap especially with all the legal liability and regulation certification for the manufactures. Imagine the legal liability of thousands and thousands of battery packs and cheap chargers very few folks actually watch. I bet many plug the bikes in and go to sleep.