60 interlaced fields per second, not 30 frames per second. The two fields do not necessarily contribute to the same frame.

In the UK the two earliest channels (BBC1 and ITV) continued to broadcast in the 405 line format (in addition to PAL) until 1985. Owners of ancient televisions had 20 years to upgrade. That doesn't seem unreasonable.

I understand the origin of the 29.97 frame rate. They did have a choice, though: Shift the audio signal's frequency and orphan the (relatively limited number of) receivers at the time, or saddle generations of people with this dumb frate rate.

An engineer at RCA in New Jersey told me that at the first(early) NTSC color demo the interference was corrected by hand tweaking the color sub-carrier oscillator from which vertical and horizontal intervals were derived and the final result was what we got.

The interference was caused when the spectrum of the color sub-carrier over-lapped the spectrum of the horizontal interval in the broadcast signal. Tweaking the frequencies allowed the two spectra to interleave in the frequency domain.

understanding the affect of the 1.001 fix has given me tons of job security. That understanding came not from just book learning, but OJT from working in a film/video post house that had engineers, colorists, and editors that were all willing to entertain a young college kid's constant use of "why?". Then being present for the transition from editing film on flat beds to editing film transfers to video. Part of that came from having to transfer audio from tape reels to video by changing to the proper 59.94Hz or 60Hz crystal that was needed to control the player's speed. Also had a studio DAT deck that could slow down the 24fps audio record in the field to playback at 23.976.

Literally, to this day, am I dealing with all of these decisions made ~100 years ago. The 1.001 math is a bit younger when color was rolled out, but what's a little rounding between friends?