1.) Majority as in Internet Explorer/Edge, Google Chrome, Safari, and Opera.
All are under closed sources licenses that would make them GPL if they
included this. The only exception would be Firefox, which is under the GPL
friendly MPL 2.0.
2.) I'm talking about photo viewers in Windows and Mac mainly, which is the
majority of desktop users.
3.) Photoshop and Illustrator come to mind. Those are the only ones that
matter to pretty much all students and professionals in design.
4.) We all know the Apple won't have GPL software on it. Android phones that
you get from your carrier won't either as that would mean that the custom
code that AT&T, Sprint, and Verizon add to their phones would be copyleft.
Android is just a base to them and the rest is all them.
