CIE XYZ is mainly a mathematical color space for describing human color perception, not a set of physically practical sensor or display primaries.

For capture, camera sensors record light through real filter dyes whose spectral responses are determined by manufacturable materials. Those filters are then transformed by profiling/raw conversion into standard color spaces. Direct XYZ-style filters are not practical because ideal XYZ responses are not based on real, clean primaries; XYZ includes “imaginary” components used to avoid negative values in color matching math. In practice, making sensor filters that behave like XYZ is difficult, can have poor transmission, higher noise, and problematic spectral responses under spiky light sources.

For displays, the same issue applies: displays need real light-emitting primaries. XYZ is not a practical set of display primaries, and efficient XYZ-style filtering would also require a very smooth light source spectrum.

So cameras and displays use real-world RGB-like primaries because they are physically achievable and efficient. Color management then converts between a device’s native responses and spaces like XYZ, sRGB, or Adobe RGB. In other words, cameras don’t need to capture XYZ directly; they capture with practical filters and map the result into standard color spaces later.