windows install py.exe

[snippsat]

Why does the default install put py.exe, pyw.exe, and pyshellext.amd64.dll in the \\Windows directory?

Because of easy access to other Python version installed.
Main version in Path is always access with python all other version use py.

λ python -V
Python 3.7.0

C:\
λ py -3.4 -V
Python 3.4.2

C:\
λ py -2.7 -V
Python 2.7.9

λ # Using pip to install to 2.7                                                                            
λ py -2.7 -m pip install logzero                                                                               
Requirement already satisfied: logzero in c:\python27\lib\site-packages

# Just pip always install to main version in path
C:\
λ pip -V
pip 18.0 from c:\python37\lib\site-packages\pip (python 3.7)

See that i have full access to all version,no need to change directory or do change to files of Python versions.

This can also create huge problems if you have multiple versions of Python installed (Py3, Py2, Anaconda2, Anaconda3).

No py will not interner with Anaconda.
Anaconda use python.exe to execute.