I'll allow your joke, but NTSC is 60 fields per second, and PAL is 50. Certainly a large portion of content came from film and in PALworld would be shown as even and odd halves of a frame, or in NTSCland as 3 halves of a frame, then two halves...

But actually interlaced content exists too. Each field is independent, there's no frames to speak of.

Early video game systems based on NTSC/PAL ran at 60 fps or 50 fps, but ran off-spec signals to always hit the same half of the display lines (odd or even). 4th gen systems (genesis/mega drive and snes/sfc) had a few games that used interlaced output; later systems had many, running PAL@60Hz became a common option too.

Not only was it built around AC, the technology at the time only allowed for roughly 1/2 the AC cycles rate. People think there was some great reasoning behind 30fps. It was just what was available, essentially.