Yes and then you are using a packaged version. But those hosters don't use a packaged version. So yum update doesn't work. I would definitely advice everybody to use a package manager, because that helps you keep everything secure ;)
Because PHP au contrary to Apache returns the full packaged version (so PHP packaged version are easier to check out). Also having e.g. OpenSSH ubuntu version strongly suggest you are using PHP ubuntu version. In that way we could cross out some of the packaged versions.
How do you know that they don't? You state it, but you offer no proof to support that.
The dominant control panel on the web is cPanel, which offers no ability to used packaged versions of PHP, Apache, or any of its extensions. They have a special interface used to pull in everything (sources, and even custom patches from cPanel) and compile it on the server and install it directly (configuring PHP, Apache, and any of the chosen extensions) automatically.