It's interesting to compare this to Microsoft's languages (e.g. C#). They give away the platform (other than the OS, of course) for free and make their money on development tools (Visual Studio, Team Foundation, etc.)
They can do that because they have integrated commercial software into the platform. When someone is using .Net, there's a high probability that it will run on a Windows server and probably also use MS SQL. That's where they get their money from. In the Java world they are more likely to use open source alternatives like MySQL and PostgreSQL, rather than Oracle
