No, they don't just seem to: Phillips was specifically designed to cam out. It was invented for this very purpose. When you're cursing with a Phillips screw that's stripped-out, you need to know that the fastener is doing exactly what it was designed to. The problem is people expecting these screws to be easily removable; that was never the intention. And the other problem is people using them for applications where they might want to remove them one day; that again is contrary to the design goal and intended use of the Phillips screw.