Because slashes (//
) were around long before their backwards counterpart came along.
EDIT:
Well, it was a nice theory, but according to Wikipedia:
- "The name "slash""slash" is a recent development, first attested in American English c. 19611961" ref
- "Bob Bemer introduced the """
\
" character into ASCII on September 18, 1961, as the result of character frequency studies." ref Bemer's own account
The /
symbol was around for centuries before it got this name, which (I'm guessing) contributed to it getting the unmarked "slash"slash name while the novel \
got the marked "backslash"backslash name.