Does anyone know why old aeroplanes used the plastic tube style of headphones, instead of copper wired? From the blog post, it makes very good sense why the MRI headphones are necessary in that setting.
> Cost: one speaker and tubes was probably cheaper than 200.
I'm pretty sure there were 2 speakers in each arm rest. I think it's more about them being harder to break and cheaper to replace. When I flew on an airline that used them, they came clean in a sealed bag. They may have been brand new, or at least cleaned and sterilised. Electronic headphones are unlikely to be as cleanable.
Cost: one speaker and tubes was probably cheaper than 200.
Weight: old headphones were chunky, see above.
Comfort: not wearing giant chunky headphones you weren't accustomed to might have been preferable
Breakability: pneumatic headphones were harder to break, cheaper to replace
Stealability: passengers would have no reason to steal the headphones, and if they did it was cheap to replace.
All of these go away as proper headphones get increasingly small and cheap.