I believe all NTSC equipment is required to support Black&White System M signals, which are exactly 60Hz[1]. It probably made their equipment much simpler to fo

I believe all NTSC equipment is required to support Black&White System M signals, which are exactly 60Hz[1]. It probably made their equipment much simpler to forget about colour encoding entirely. (And it made the 44,100Hz fit too) [1] http://en.wikipedia.org/wiki/CCIR_System_M http://en.wikipedia.org/wiki/CCIR_System_M