I also thought this seemed extremely odd. Here is an unoptimized example, built ...

I also thought this seemed extremely odd.

Here is an unoptimized example, built on an M1 Mac:

    $ cat <<EOF > Dockerfile
    FROM python:3.12-slim-bookworm
    RUN apt-get update && apt-get install -y python3-pip
    RUN pip install pandas
    LABEL "name"="python-pandas"
    ENTRYPOINT ["python3"]
    EOF

    $ docker image ls -f 'label'='name'='python-pandas'
    REPOSITORY               TAG       IMAGE ID       CREATED         SIZE
    sgarland/python-pandas   latest    89e31f6eb83d   9 minutes ago   764MB

A more optimized version:

    $ cat <<EOF > Dockerfile
    FROM python:3.12-slim-bookworm
    RUN apt-get update && \
        apt-get install -y --no-install-recommends python3-pip && \
        pip install pandas && \
        apt-get purge -y --autoremove python3-pip && \
        rm -rf /var/lib/apt/lists/*
    LABEL "name"="python-pandas"
    ENTRYPOINT ["python3"]

    $ docker image ls -f 'label'='name'='python-pandas'
    REPOSITORY               TAG       IMAGE ID       CREATED          SIZE
    sgarland/python-pandas   smaller   102308842b88   4 seconds ago    342MB
    sgarland/python-pandas   latest    89e31f6eb83d   27 minutes ago   764MB

Even adding in scipy didn't crack 500 MB:

    $ docker image ls -f 'label'='name'='python-pandas'
    REPOSITORY               TAG       IMAGE ID       CREATED          SIZE
    sgarland/python-pandas   scipy     808535284f03   3 minutes ago    497MB
    sgarland/python-pandas   smaller   102308842b88   9 minutes ago    342MB
    sgarland/python-pandas   latest    89e31f6eb83d   36 minutes ago   764MB

I'm not sure how they managed 10 GB. Here's the non-slim version, with no optimizations (this is much larger because `python3-pip` has the system default Python interpreter as as dependency, so this installs Python3.11 into the image):

    $ cat <<EOF > Dockerfile
    FROM python:3.12-bookworm
    RUN apt-get update
    RUN apt-get install -y python3-pip
    RUN pip install pandas scipy
    LABEL "name"="python-pandas"
    ENTRYPOINT ["python3"]
    EOF

    $ docker image ls -f 'label'='name'='python-pandas'
    REPOSITORY               TAG       IMAGE ID       CREATED          SIZE
    sgarland/python-pandas   bigger    f8f98e9a241c   8 seconds ago    1.44GB
    sgarland/python-pandas   scipy     808535284f03   3 minutes ago    497MB
    sgarland/python-pandas   smaller   102308842b88   9 minutes ago    342MB
    sgarland/python-pandas   latest    89e31f6eb83d   36 minutes ago   764MB