Different distros require different metadata for their packages. But in general amongst the top 10 distros, almost all metadata in a package is optional. You don't have to specify the URL where it came from or who the author was in order to get a package accepted. Some distros do require a URL, mainly because they build from source to install on a system. But other distros merely accept a source-package which bundles the source code and that's built on their build servers and released after being peer-reviewed. But the peer-review is a manual process, so it's human-fallible.
As an example, let's compare the way two distros (Fedora and Debian) package an old piece of software: aumix.
Taking a look at this spec file [1] for fedora, we see two pieces of metadata: a URL to a homepage, and a URL to the software. The URL is not used for packaging at all; it's merely a reference. The URL to the file can be used to download the software, but if the file is found locally, it is not downloaded. And guess what? That source file is provided locally along with the other source files and patches in a source package. So whatever source file we have is what we're building. This file doesn't contain a reference to any hashes of the source code, but the sources file [2] in Fedora's repo does.
With Debian we have a control file [3] that defines most of the metadata for the package. Here you'll find a homepage link, which again isn't used for builds. The path to a download is contained in a 'watch' file [4], which is again not referenced if source is provided, and generally only used to find updated versions of the software. There are no checksums anywhere of the source used.
The source to aumix actually provides its own packaging file [5], provided by the authors. Apparently the URL used here is an FTP mirror, not the HTTP mirror provided by the earlier packagers. Could that be intentional or a mistake? And could they possibly be providing different source code, especially considering the hosts themselves are different?
It's clear that there's a lack of any defined standard of securely downloading the source used in packages, much less a way of determining if the original author's source checksum is the same as the packager's source checksum. There are several points where the source could be modified and nobody would know about it, before the distro signs it as 'official'.
These are all good details about how much information various distros give me, the user, about the sources they're using for their builds. I certainly agree that it would be nice for them to give a lot more.
But this is still secondary to the basic point: as a Linux user, I get packages from my distro, not from the upstream source, so I don't have to go searching around the Internet for packages or package updates, wondering whether I've got the right source, wondering why there isn't an https URL for it, etc., which is what Windows users have to do according to the article (and OS X users too, for the most part, though the article doesn't talk about that). The distro does all that, and either I trust them to do it or I don't (in which case I go find another distro). The fact that the distro doesn't make it easy for me, the user, to see how they verify the sources they use, does not mean they aren't verifying the sources they use.
Also, while it's true that the distro verification process is human-fallible, as you say, and it would be nice if every OSS project made it easy for distros to automate the process instead, it's still a lot less human fallible than having every single user go searching around the Internet for software. Distro packagers at least have some understanding of what they're doing, and they at least know who the authoritative source for a particular package is supposed to be without having to depend on Google's page rank algorithm.
Yes, Linux software is generally less prone to erroneous installs than Windows software, when it is done through your distribution. However, I think a parent commenter was pointing out how much easier it is to hack all of the users with this unified system of installation.
Is searching for, downloading and installing Putty actually resulting in users with malware-laden files? It would seem not, as the highest-ranking results for Putty are the official ones, and downloading/installing is a breeze once you get to the official page.
For software that's a more likely target for scams (like Firefox) you'll find a lot more user error and potential for abuse. And consider that many users may download and install Firefox by hand instead of using their distro (it's faster and less complicated). And similar to the attack on popular Windows end-user software, Linux server software is often a more high-value target for attack also results in users unknowingly installing insecure software, as we've seen in[1] many[2] cases[3].
Realistically the only thing keeping Linux more safe is that the user base and culture are different. But it would be naive to assume that somehow distro packagers are a more trustworthy source of files than the ones you could find on your own. It would seem to completely depend on the application and the user.
Do you have any actual evidence that Linux distros do packaging this way?
But I'm also a packager, and I have some awareness as to how one would go about pwning all users of my distro.
And do you actually do so? If so, please tell me which distro you package for so I can avoid using it. If not, why do you think other packagers do?