It seems to me like the files run the same without that line.
If you have installed many versions of Python, then #!/usr/bin/env ensures that the interpreter will use the first installed version on your environment's $PATH.
If you are using Unix, an executable file that is meant to be interpreted can indicate what interpreter to use by having a #! at the start of the first line, followed by the interpreter (and any flags it may need).
For any other operating systems, of course, this rule does not apply (but that "shebang line" does no harm, and will help if you ever copy that script to a platform with a Unix base, such as Linux, Mac, etc).