The correct explanation is that in the dairy, a lot of pressure is applied on the milk so as to break the large fat globules of the milk into very small size. Due to the small size, the rate at which the fat globule rises to the surface (the fat has lower density than water and therefore tends to rise to the surface of the water) gets much decreased. Due to this, the fat is unable to rise as a separate layer to the surface and remains suspended within the milk.
On the other hand, milk directly from the animal has large fat globules and due to their large size, they promptly rise to the surface of the milk, leading to a thick cream layer.
Regards,
Urmila.