There are a bunch of minor differences between software and music that make software more viable as a business when using the same definition of property. Software companies often sell services that are wholly based on software, but it's the service that has value. Customized software such as an internal accounting system is worth more to the purchaser and often not worth anything to the world at large. It's also easier to use the old definition of property to sell because it's easier to prevent unauthorized users from using software.