Actually the ASI shows ‘ASIR’, or ‘Air Speed Indicator Reading’.
Correct for instrument errors and you will get IAS, in other words what a perfect instrument would read.
Correct for pressure error and you get RAS (or CAS for Americans).
Correct for compressibility and you get EAS.
Correct for density and you get TAS
Correct for wind component and you get GS
But to return to the subject of the thread, I too found it unhelpful back in the day when some US manufacturers marked the ASI dial with colo(u)red arcs, referenced to CAS instead of IAS.