Few commands that need to do
sudo remind you that "You do not have the privilege" or "Are you root?" etc.
while a few commands do not give such message. For example, if you do
fdisk -l instead of
sudo fdisk -l ubuntu does not give any message. This is particularly confusing for people who come from different linux distro (eg: CentOS, RHEL etc.).
Wouldn't it be a good idea to notify user each time he commits such mistake, that he/she must be a sudoer to execute that particular command.