[ddalex]

Most of the machines out there are single user, and managed by that user, not by a professional sysadmin. As such, the user has the needed access (root) to install any programs that they want, and all modern OSes allow only the admins to install programs.

We already put multiple warning messages when a user decides to execute a suspicious binary, and yet everyone still clicks through any prompt without the second thought ?

What's your suggestion that a). allows any user to have the machine installed and configured as he wants? and b). do not allow random programs from executing ?