Photon Timelessness
I often hear that "a photon experiences no time" and that, from the photon's perspective, emission and absorption are instantaneous.
But since a photon has no valid reference frame in special relativity, isn't "the photon's perspective" just a figure of speech?
Light from distant galaxies has clearly traveled for billions of years according to every measurable clock. So is "a photon experiences no time" a real physical statement, or simply a mathematical consequence of proper time being zero along a null worldline?
More generally, I sometimes wonder whether we treat certain consequences of equations as physical truths when they may simply be mathematical features that keep the theory internally consistent. Is this one of those cases, or do physicists consider it a genuine statement about reality?