More generally, it's a characterset / collate sequence thing. Specifying a range with a start and end point requires understanding what that range specifies. Which can change depending on context, locale, characterset, etc.
In the case of EBCDIC, there are several places in the alphabetic collation sequence in which non-alpha characters are interspersed among the letter codes. Most notably between R & S, though it appears that I-J also includes a standout. The fact that there are multiple incompatible forms of EBCDIC doesn't help matters much.
