Scientists film whale giving birth while other whales work together to help her

Maybe? The article only seems to note buoyancy assistance for the mother whale - not that whales have prehensile tails or anything, to do a lot more.

Vs. elephants have trunks. They normally use those to handle their young. The action barrier for an elephant matriarch, observing that another elephant is having problems in the final stages of delivering her calf, is very low.

Maybe you're right, and it just doesn't happen? But it seems like you'd need a lot of closely observed elephant births to establish that fact.