Guest writes in 2005:
The screens were supposed to be FLAT since the very begginings of the TV (including those B/W ones), but they couldn't solve the picture distortion problems, so all TV's were made with the screens shaped as a cut of a sphere.
The first to address these problems was SONY making so called TRINITRON screens, which were shaped as a cut of a cylinder, but also making it proprietary, which made it very expencive for everyone else to produce it (TYPICALLY SONY). Only a few very expencive computer monitors were produced as TRINITRONs (NOKIA, NEC, PHILIPS). To solve the distortion problems, SONY stored the correction patterns in EEPROM, reading it repeatedly while displaying lines/frames (Everyone who had fixed older TRINITRON monitors & TV sets knows how complicated those circuits were).
The new TV sets might have really flat screen (sometimes marked as "PURE FLAT"), but the producer had to solve the distortion problems, including the FOCUS correction during each line (that must be complicated - regulating 5kV voltage at 15kHz or higher). That's why so many those "FLAT" screen TV's have actually distorted picture. Go to any consumer electronics shop - if you find more than 10% TV's WITHOUT ANY DISTORTION, I'll buy you a lunch!