Open source Unix systems are the kings of package management. OS X pretty much does the exact opposite of 'package management', and any third party solution is based on existing Linux and BSD implementations.
This is something I keep hearing, and I keep linking to the same thing. "Download and One-Click Install" can easily be done on Linux. In fact, that's even what it is called: "One Click Install", at least as far as openSUSE is concerned.
Explanation: http://en.opensuse.org/openSUSE:One_Click_Install
Example: http://software.opensuse.org/package/chromium
Bonus: It still adds a repository so you have a working update path that plays nicely with the centralised package management that lets you manage every single package centrally, instead of having half a gazillion individual updaters, bundled libs etc.
Let's say you wanted to install Google Chrome. On OS X, you go to chrome.com and click the single "Download now" button, and it downloads.
On Linux, you get the same button, except clicking it takes you to another screen where you have to know whether you are a "Debian/Ubuntu" or a "Fedora/openSUSE" user or need a "community supported" version, and whether you want the 32 bit or 64 bit version, and whether you want to "add the Google repository to your system", and here's a thing to run on the command line if you don't want that.
The "sudo apt-get install yadayada" stuff is legitimately great for power users. But for most consumers, the OS X approach is definitely to be preferred.