I don't know about your culture, but I've never heard anyone use 'sql server' when they meant 'the database server'. You just don't call it that. I also think it's a pretty dumb product name. You might as well call a web server 'html server'.
People not familiar is Microsoft are probably not taking part in a discussion on HackerNews, let alone a discussion of why their SQL Server product was not ported to *nix.
We call the generic category "SQL Server" belongs to: database servers, or relational database servers.
No one uses "sql server" for something besides naming that specific MS product.