Long one!
Many of the radios pictured in this chapter are shortwave units, which have fallen out of common usage in the last 50-60 years as the speed and amount of information available via other media has increased. However, for years, many governments operated official (or allowed semi-official) stations on a designated frequency, and so radio manufacturers would indicate those respective countries as points on the dial - see page 2's radio and several of the examples on page 30. Here's an older example from a five-band unit (an American Philips from just before WWII). Note the top band is AM, and gives both frequency in kilocycles (or kilohertz, like used in the US) and wavelength in meters (like many European stations), and also runs 'backwards' compared to normal US practice today (the low frequency is on the right).
The 648kHz band given in the image on page 46 would be a 463m signal (rounding), at the lower end of the modern AM band (and not far from where the tuning indicator is on the image above).
AM was the dominant band through much of the west into the early '70's, as FM circuitry was comparatively complicated (and therefore more expensive), particularly when stereo multiplexing was used, and FM signals have a comparatively very limited range. I would guess that most of the radios pictured in this chapter don't have FM bands. However, the higher fidelity possible with FM, the decrease in the cost of the broadcast equipment needed, and the advent of cheaper solid state components capable of handling the higher frequencies used in decoding the signal led to the rise of FM through the '70's, and today AM is largely used for talk/sports and low budget stations here in the US.
Thanks very much for the chapter and the excellent notes - glad to know this series is being given the chance to continue by the publisher!