The hole is too small. The diameter of the hole should be at least 2 and preferably 3 or more times the diameter of the root ball. The hole should be shaped like a shallow bowl, not a vertical column.
Roots grow primarily near the surface.
Loosening the soil as far as possible away from the trunk will make it easier for the roots to grow and establish. The tree is planted too deep. Soil beneath the root ball should not be loosened or prepared. The hole should be dug only as deep as the root system otherwise the ball will settle and the root collar will again be too deep. The soil dug from the hole should only be loosened and broken up then back filled around the root ball.