The state says, “installing the drain tile on the inside of the footing is known as cosmetic.”
The code also requires that the contractor installs 4 inches of rock or gravel under concrete floor.
But if you have a high groundwater table on your lot 4 inch of rock is not enough.
If water touches the concrete floor it will wick up to the topside of the floor and evaporate into the house air rising your humidity level.
This in turn creates other problems in the house. If there is carpet on the concrete floor it now has mold growing in it.
Moisture freezing on the windows in the winter time. By installing 4 inch rock you leave larger voids under the floor not giving the water a chance to touch the concrete floor. This is required in Minnesota building codes since 1992.
Now installing draintile around the foundation on the inside is known as cosmetic it also is wise and while you are installing draintile running additional draintile lines is just prudent.
The cost worth the investment of only about $ 150.00.