Why are there flotation devices under plane seats instead of parachutes?

"Excuse me, is that rat tart? Yes. Disgusting!" --Monty Python

"Aieee! Sunlight! Turn it off! Turn it off!" -- Sheila Bungee

Like a bat out of hell, I'll be gone when the morning comes - Meat Loaf

Dawn, nature's gentle hint that it's time for bed.