I don't think many people saw NBC's 1955 color shows in color, as color TV was still a novelty in the 1950s. Only thing I can figure is RCA was using these shows to promote color TV programming produced under the RCA color standard.
CBS color didn't make it out of the gate.
It wasn't until RCA's compatible color TV standard, in which color programs could be viewed directly as b&w, took hold that color television really took off in this country. The CBS color system flopped probably because it was not compatible with black-and-white televisions. What did viewers of CBS color shows actually see on their b&w sets, if they received a picture at all?
I would think they would see a picture of some sort, as the stations would never hear the end of it if color programming produced a blank raster on black-and-white sets tuned to CBS color programming.