A large majority of the frequencies were assembled and tested on devices that couldn't hit high frequencies. Take for instance the CAFL database. Many of the sets were assembled using research on devices with far less capability than what we have access to today, many topping out at 100 kHz.
Sure Rife has the capability to go higher, and his frequencies reflect. However, after the technology was pushed underground, people had to make do with what they could get or build.
Even today, most plasma devices have a fixed carrier wave that rely on audio ranged modulators. This begs that research using said devices would produce a list of low frequencies. Even worse when one doesn't know it was developed as a modulator and then tries to use it as direct frequencies.
The SC is the first to be able to recreate direct frequencies above 400 kHz, all the way to 3.5 MHz directly.
For each frequency program, you can sometimes dig up the history if you dig deep enough.
However, a lot of that is now changing with Spooky2. Take for instance the MW and BP databases. The frequencies are too high for our current level of tech, and so we use sub harmonics for now. However, at least we can target sub harmonics of those frequencies all the way up to 25 MHz.
Another thing to consider is that HC determined that most pathogens live between 76 kHz and 880 kHz. Even Rife's frequencies do not go much over 2 MHz.
For more details, please check the link: