Mac OS X administrator account still requires sudo when trying to install Ruby, Vagrant, and Grunt using terminal I am still required to use sudo on my installs. I am sole proprietor of the laptop and have an administrator account. Shouldn't I be able  to install software without using sudo?
Even though the account is an administrator, you still need to use sudo to become the root user. Administrator still has restrictions on what files can be read or written to.

For example, the /System/Library/User Template/ folder is set to System: Read/Write and even though you are an administrator, you won't be able to open this folder without either changing the permissions or using sudo to become the root user.