Because not all "developers" are developers in their day jobs. I'm personally a sysadmin most of the time, and I do my own R&D (mostly academic, but novel). So

Because not all "developers" are developers in their day jobs. I'm personally a sysadmin most of the time, and I do my own R&D (mostly academic, but novel). Some tools I like are not free, and I buy licenses by myself.