Why are many operations or commands in Ubuntu not allowed normally when you can just do the same thing by typing sudo?

Question

What purpose does this server when bypassing is as easy as typing sudo?

Forgive the naivety here but I am a rookie and I'm sure there has to be a good reason for this, and I'd like to know that.

Answer 1

Security! ;-)

Only admin users can do sudo and even those have to provide a password, i.e. if you leave your screen for a minute, nobody can do sudo without the password.