Why can’t Python’s raw string literals end with a single backslash?

Technically, any odd number of backslashes, as described in the documentation.

>>> r'\'
  File "<stdin>", line 1
    r'\'
       ^
SyntaxError: EOL while scanning string literal
>>> r'\\'
'\\\\'
>>> r'\\\'
  File "<stdin>", line 1
    r'\\\'
         ^
SyntaxError: EOL while scanning string literal

It seems like the parser could just treat backslashes in raw strings as regular characters (isn’t that what raw strings are all about?), but I’m probably missing something obvious.