ROS is a helper framework, for people who would otherwise be implementing low-level embedded interfaces to arbitrary hardware, so that they can share more of their work.

It's like Rails, if instead of targeting the web your deployment platform were an unmanned autonomous submarine vehicle.

And you needed to support a donated Russian sonar, some second-hand one-off logic boards, some sensors you soldered together in your lab, and implement a navigation algorithm you only have in research paper form.