two questions after returning from a trip

1) Why do airplanes need a separate kind of headphone plug? If they didn't, people would be more inclined to use their own headphones, and the airline wouldn't have to hand out disposable headphones on the flight. (They are disposable; if you give them back, they go straight into the trash). This bugs me. Why does it make sense to them? Economically: say 300 pair x $0.50 cost to the airline = $150 could be saved on each long-haul flight. How much would it cost to retrofit the planes for regular 3.5mm stereo headphone jacks? Say a highball $100 a seat- it would pay for itself in 200 flights. I remember when the airlines used to sell the headphones, but now they just give them away. I'm sure it's not an image thing; it sure isn't glamorous to rip into a packet of headphone.

2) Why do washing machines have a separate dial for clothing colour when they already have a setting for temperature? If I set "hot/cold" and "colours" does it modulate the hot temperature downward? I don't tend to think it does, since the water feels just the same whether it's on "whites" or "colours."

To tie these two questions together, if I'm going to accidentally send a piece of electronics through the wash, I'm really happy it was my headphone airplane adapter.