As a person who actually has dug by hand in the soil of Minnesota, I wonder what the soil is like en route from Isanti to the Twin Cities?
Where I live, it is clay. You cannot dig without hitting rocks of various sizes. And if you are anywhere near a tree, there are roots. Digging is very difficult.
If the soil is sandy or a loam, that is a whole different thing.
People who operate backhoes for a long time are so good that they can feel with the bucket if soil has been disturbed. Soil that has been disturbed can be seen by those who know what signs they should see.
Digging in that backyard would be about impossible, I feel. And since the soil is disturbed all over, there would be nothing that stands out.
I don't know if it is true there, but in many developments, the topsoil is scraped away and sold. What is left is the subsoil which is like iron