Something I've been wondering for a while, why do no (or at least not many) phones/tablets use transreflective LCD displays, and instead rely on using several watts of backlight to make the screen visible in daylight? My Garmin GPS uses one, and they've done it for years so it's not like the technology isn't there.

Basically it allows you to completely turn off the backlight in daylight, instead reflecting ambient light back through the screen.

Is it something to do with pixel density/colour rendition? I originally thought it might have been cost, but it no longer makes sense considering the price of modern phones...