Can't run lpr from python on windows 2012 server

[loial]

I am reposting this question in a simpler form.

I can run lpr from the command prompt but not from python

os.system("notepad") works
os.system("lpr") does not work. Basically it says lpr is not a known program or executable

Why can I run lpr from the windows command prompt but not from python(2.7)