Linux based OSes don't let you install software from a new repository without adding their keys to your system. This is for the user's own security. Blocking 3r

Linux based OSes don't let you install software from a new repository without adding their keys to your system. This is for the user's own security. Blocking 3rd party tracker cookies by default is a similar decision. Sometimes developers have to protect users from choice overload and choose sensible defaults.