It's not like this question has a "right" answer, because we are describing different models as "perceptual" or "physical".
The same phenomenon happens in audio. The vast majority of musical synthesizers either model the perception of sound or the physical production of sound. For example, you can model a piano as a physical system with a vibrating string, or you can model it as a subjective phenomenon, constructing a frequency spectrum that sounds similar using FM synthesis, subtractive synthesis, additive synthesis, et cetera--none of which correspond in any meaningful way to the piano itself, we're really trying to trick the ear.
In the same way, I see RGB as a simplified physical model rather than a perceptual model, because it does correspond rather closely to physical reality, and it corresponds somewhat poorly to subjective reality. You can construct RGB as a simplification from a continuous spectrum model of radiation, all you have to pick the spectrum of your primaries. From there, you can use the RGB model in your physical simulations, such as ray tracing and photon mapping. Lab color does not work well for ray tracers because it does not correspond to physical reality: it is fairly nonlinear, and the coordinate system is awkward.
Likewise, RGB is a poor model for subjective perception (compared to Lab or XYZ) because its gamut is limited, and differences in RGB space do not correspond well to differences in subjective qualities. You can see how awkward RGB is for perceptual modeling whenever you use a color picker. It is frustrating to try and construct a pleasing palette of colors by dragging around RGB sliders, or even HSV/HSL sliders, because the model is so far from subjective perception that doing something conceptually straightforward, such as altering hue or matching luminosity, requires fiddling about.
In short, the description of RGB as a "physical model" is because we use it for physical simulations, as well as for working with hardware such as monitors and cameras. My description of Lab, CIECAM, XYZ, etc. as perceptial models are because we use those for modeling the subjective perception of color.
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I clearly misunderstood what you mean by "the physical phenomenon of light".
You seem to mean: "a common engineering method of displaying colors to the human perceptual system"
while I thought you meant: "the physical properties of the visible band of the electromagnetic spectrum"
It's not like this question has a "right" answer, because we are describing different models as "perceptual" or "physical".
The same phenomenon happens in audio. The vast majority of musical synthesizers either model the perception of sound or the physical production of sound. For example, you can model a piano as a physical system with a vibrating string, or you can model it as a subjective phenomenon, constructing a frequency spectrum that sounds similar using FM synthesis, subtractive synthesis, additive synthesis, et cetera--none of which correspond in any meaningful way to the piano itself, we're really trying to trick the ear.
In the same way, I see RGB as a simplified physical model rather than a perceptual model, because it does correspond rather closely to physical reality, and it corresponds somewhat poorly to subjective reality. You can construct RGB as a simplification from a continuous spectrum model of radiation, all you have to pick the spectrum of your primaries. From there, you can use the RGB model in your physical simulations, such as ray tracing and photon mapping. Lab color does not work well for ray tracers because it does not correspond to physical reality: it is fairly nonlinear, and the coordinate system is awkward.
Likewise, RGB is a poor model for subjective perception (compared to Lab or XYZ) because its gamut is limited, and differences in RGB space do not correspond well to differences in subjective qualities. You can see how awkward RGB is for perceptual modeling whenever you use a color picker. It is frustrating to try and construct a pleasing palette of colors by dragging around RGB sliders, or even HSV/HSL sliders, because the model is so far from subjective perception that doing something conceptually straightforward, such as altering hue or matching luminosity, requires fiddling about.
In short, the description of RGB as a "physical model" is because we use it for physical simulations, as well as for working with hardware such as monitors and cameras. My description of Lab, CIECAM, XYZ, etc. as perceptial models are because we use those for modeling the subjective perception of color.