Are you guys somehow saying that it's standard practice or expected for dealers in the US to not sell or deliver tractors in the US with loaders and nothing on the back for ballast? I think not. They sell you what they can/you want not necessarily what's safe.
My read on that led me to think there was more to it. #1 the dealer knew these guys were new to tractors, so YES to what you said or at least have a discussion about rear ballast. Even worse, #2 the bucket is WAY TOO #$*&# HEAVY for that tractor. NO $#*& EXCUSE for selling them that bucket.