Is this a troll or what? I'll take the bait.
I don't know where you obtained the information on concrete pool construction but there is no fill dirt problem. After the hole is dug to the shape of the pool rebar is placed a few inches away from the existing dirt and either gunite or shotcrete are sprayed directly onto the dirt that is there and built up to a certain thickness. Certian climates add more rebar for area that are prone to freeze thaw cycles.
Your comments may be more accurate for a Fiberglass pool where fill is added after the shell is installed and the forum has had members who complain about bulges in the pool or uneven settling.