为什么二进制文件中的构建不需要Root访问权限？

When I am in my dept's server, I cannot use commands such as "apt-get install nethack". I have to build the nethack from Binary files to get it working, at least so I have been told. I cannot understand the reason. Why do I need to build things from binaries? Why is the use of the commands, such as "apt-get", forbidden? Why do I not need Root access to build from binaries?When I am in my dept's server, I cannot use com