No two Linux package managers are identical either, and not all Linux distributions work like Debian. Debian is a collection of volunteers. The choice to trust it is no different to the choice to trust Homebrew. Considering the package manager to be part of Debian doesn’t change this.

However none of this has any relevance to the claim in question, which is that python must be installed manually.

MacOS certainly has a package manager that can install and maintain python.