@bob Here's a simple pertinent example : I have 2 devices I use connected to my TV. One is a installation of kodi in the form of osmc on a raspberry pi, the other is an Amazon fire TV box. Both have the capability to be remotely controlled via the LAN with an app on my smartphone. The app for kodi is called "Kore" and is free software (get it from f-droid). The other is Amazon's proprietary remote app, available from their app store. Kore just works as you would expect. The Amazon version requires me to (a) install a load of other Amazon shit I don't want on my phone, and (b) login to the remote app with my Amazon credentials when I use it!! They either want to control what I do with it, or spy on what I do with it or both.
That's proprietary software vs free sotware for you in a nutshell.