The court rulings are based on telephone directories and the conflicts between their disparate companies (including Ma Bell). The phone company tried to claim that they owned the phone numbers (and any derivative intellectual property rights). The companies that published competing phone books successfully argued that the only property rights exist in the compilation of data - not in the data itself. The result of this pile of history is that whosoever owns the computer owns the data on that computer.

The GDPR comes from the opposite direction - you own the data about yourself.