It is for all the many (many, many, many, many) applications of that kickswitch. There was no difference between an "A-body" kickswitch, a "B-body" kickswitch, a truck kickswitch, etc. This kind of switch was used over a long span of time, without application specificity. This is exactly what is meant by "Specifications are subject to change without notice". The shape of the kickbutton does not affect the fit or function of the switch, and so there was no reason to discern those two varieties (or any of a great many other variants) on the assembly lines, in the parts books, or in the parts pipeline.
That means if you want a switch that looks exactly like the one the car came to you with, you will need to keep fishing. Think about the obverse, though: it also means there was (and is) no way to look at the kickswitch in any given car and say "That's wrong!".
FWIW, I have owned two low-low-miles A-bodies with the flat-sided kickswitch button.
