some hosting providers pay a fee to have some installs available to their clients,, (that be me and you-all)
But, most stuff is open source or free for many uses. I like installing things myself so I learn more about it.

i use phpcoin - its kinda clumsy and cute at the same time - blardy pain in the wotsit to set up tho - do like the recurring invoices and my list of soon expiring domain names...