Because there is no copyright protection for the general idea of an interface!
This isn't actually true, you can patent interfaces. Notoriously, a TV channel guide which has a grid interface with channels and times represented as columns and rows is patented (originally by TVGuide, now owned by Rovi). Every Guide you see on a cable or satellite box in the US pays a licensing fee to Rovi.
Comments
Because there is no copyright protection for the general idea of an interface!
This isn't actually true, you can patent interfaces. Notoriously, a TV channel guide which has a grid interface with channels and times represented as columns and rows is patented (originally by TVGuide, now owned by Rovi). Every Guide you see on a cable or satellite box in the US pays a licensing fee to Rovi.
http://www.wipo.int/pctdb/en/wo.jsp?WO=1998053607
Wow, and filed in 1998? How is every spreadsheet in the world not prior art?
Don't Apple's lawsuits against Android almost completely revolve around general ideas of interfaces?