Is it really true that you can measure distance in seconds? I think light-seconds are different units from seconds hence why they measure distances, similar to how Watt-hours and Watts are not the same unit. If a second was a measure of distance then speed would be unit-less (second / second) as opposed to the speed of light which is light-second / second ≈ 3e8 m/s.
You are right, light seconds don't fit in well. My point still stands, you can't really know what physical quantity is measured just from looking at the unit alone, that's now what units are made for.
