Recursive glob?

In order to do recursive globs in bash, you need the globstar feature from bash version 4 or higher.

From the bash manpage:

globstar
    If set, the pattern ** used in a pathname expansion context will
    match all files and zero or more directories and subdirectories.
    If the pattern is followed by a /, only directories and
    subdirectories match.

For your example pattern:

shopt -s globstar
ls -d -- **/*.py

find . -name '*.py'

** doesn't do anything more than a single *, both operate in the current directory

Since Bash 4 (also including zsh) a new globbing option (globstar) has been added which treats the pattern ** differently when it's set.

It is matching the wildcard pattern and returning the file and directory names that match then by replacing the wildcard pattern in the command with the matched items.

Normally when you use **, it works similar to *, but it's recurses all the directories recursively (like a loop).

To see if it's enabled, check it by shopt globstar (in scripting, use shopt -q globstar).

The example **.py would work only for the current directory, as it doesn't return list of directories which can be recurses, so that's why you need to use multiple directory-level wildcard **/*.py, so it can go deeper.

Look here for examples of finding files recursively.