Steam launches a script to install dependencies. The expectation is that this script will be modified by distros to account for the packaging mechanism on that

Steam launches a script to install dependencies. The expectation is that this script will be modified by distros to account for the packaging mechanism on that distro, and package name differences. So if you are not on an apt based distro yet apt-get is being run, then your distro's Steam package needs to be updated. It would be nice to describe all the dependencies on the steam package itself and let the package manager handle this, unfortunately it wasn't possible on Ubuntu 12.04 because of multi-arch issues. Other distros might not have this problem.