PHP Apache on ubuntu backward paths aren't working

I've setup Apache on a new ubuntu system. The root folder for the domain is /var/www/abc/web

Inside the abc folder I've an image called logo_out.jpg and inside the web folder I've the same image called logo_in.jpg

I've a simple html file in the /web folder called index.html which contains only one line

<img src="../logo_out.jpg" alt="image"/>

which isn't working at all. It is completely weird. I did some more testings and I've noticed that ../ is never going backwards here. To make sure this, I tried this.

<img src="../logo_in.jpg" alt="image"/>

This shouldn't work normally because the filename is incorrect, but it is working. Even if I give <img src="../../logo_in.jpg" alt="image"/> it is taking the same logo_in.jpg inside the web folder.

I don't understand why this is happening. Am I missing any modules in Apache or anything?

FYI, I've PHP 5.6 with apache 2.4.29