Why No Movie Subtitles on Flights?

It's been over 10 years since captioning was introduced. One place it has consistently never shown up is on planes. The airline industry keeps saying it's too expensive to add. How hard can it be to add in subtitle/caption support? Those little TVs and wall monitors can show the words. With some airline companies, the pre-flight instruction videos are captioned or subtitled. However, the movies aren't.

The circuitry is small and simple enough to be added to just about anything out there.

http://category.alldatasheet.com/index.jsp?semiconductor=CAPTION
http://www.brouhaha.com/~eric/pic/caption/

More can also be found on Google. It's a simple matter to turn on the subtitles if there's any. But to deny others enjoyment of a movie while on a long flight?

With portable DVD players getting cheaper and better, let's hope the airlines take notice of this. Keep spare batteries with you as well. Long flights can outlast batteries at times. Same goes with laptops with DVD players. Oh, wait, the airlines have noticed this but don't want to throw any money at it. Too bad. They'll probably have more satisfied flyers if they did.