@Suiseiseki @p @scathach @lispi314 i'd imagine it's not as rare as we think it is -- as 'available' kinda depends who you are and the line between 'source available proprietary software' and 'software that has never been distributed except to a single/couple clients, along with source code but and the understanding that they could distribute it but they never do' code gets blurry
ie pretty much all the software i ever worked on in my career was of this kind - the clients had access to the source code and were allowed to do 'whatever they wanted' with it which probably could have included releasing it as GPL3 if they desired. We were that much beholden to them. But they never did.