More explicitly, how would a license that gives everyone the right to copy, modify and redistribute source code for any purpose without compensation or attribution have prevented Github from building a tool that copies, modifies and redistributes source code without compensation or attribution?
Because if you use GPL code, you must release your use/changes under the GPL. That's why the GPL is often called infectious. If copilot spits out GPL code verbatim, the user of the code must respect the license.
You don't know how the GPL works. The GPL explicitly requires attribution. I don't understand what you thought you were saying. The GPL places strict requirements on the licensing of derivative works. You don't know how the GPL works.
More explicitly, how would a license that gives everyone the right to copy, modify and redistribute source code for any purpose without compensation or attribution have prevented Github from building a tool that copies, modifies and redistributes source code without compensation or attribution?