It is easy for programmer-types to think that pixel counts are objective, simply because familiarity with units, or perhaps because pixels are discrete countable physical locations on a sensor.

An optical system composed of multiple lenses doesn't obviously correspond to a certain resolution, but the confusion is merely the literature taken at hand: instead of obsessively comparing smartphone advertisements, it is physically possible to read books and course notes on physics, optics, ...

There is nothing impossible about publishing spatial frequency responses etc, or legally mandating such information to be present on any advertising materials as soon as the MPixel counts are advertised.