The fact that www.example.com and example.com resolves to the same place is a happy accident due to someone explicitly configuring it so.
As a practical example, the website for my current employer had not configured their "bare" domain. When applying for a job I decided to check out their website, and copied only the "bare" domain and pasted it in my browser. Didn't work, just timed out.
I tried a few times and through "huh, website down for a few days, that sure doesn't look good". Then on a whim I figured I might try the "full" domain, and sure enough that loaded up straight away.
One of the first things I got done when I was hired was to ensure the "bare" domain worked.
As a practical example, the website for my current employer had not configured their "bare" domain. When applying for a job I decided to check out their website, and copied only the "bare" domain and pasted it in my browser. Didn't work, just timed out.
I tried a few times and through "huh, website down for a few days, that sure doesn't look good". Then on a whim I figured I might try the "full" domain, and sure enough that loaded up straight away.
One of the first things I got done when I was hired was to ensure the "bare" domain worked.