Just as an example, consider Hadoop and its ecosystem. Another example is Elasticsearch. There's work involved in making these platforms production-ready and keeping them and their dependencies up-to-date and ensuring all your applications in your portfolio are using the same set of software. Most organizations are not prepared to take that on. So they turn to a vendor who will do it for them for much cheaper than they could do it themselves.
That's why the saying is "free as in freedom, not free as in beer" because open source software is not free as in beer. At least not when factoring in the total costs.
The packaging argument was made in the context of complying with software licenses. Responsible companies which perform due diligence on the software they run have to track the provenance of all software that ships as part of their dependency closure. If you want to ensure you're not vulnerable to lawsuits then you can't simply apt-get stuff from a PPA. You need to build it yourself, and track exactly what goes into that build.
Meanwhile, if you opt to run managed service from a cloud provider, you don't have to bother with that because that's not your problem (or liability) anymore.
Yes, and it does indeed apply to all readily available container images.
In fact, it applies to any and all software packages put together by third-parties.
I mean, who in their right mind downloads random stuff from the internet and expects to just drop it in production software which you build your business upon?
Do people successfully lawsuit their cloud providers for downtime?