I know exactly what you mean - I can see one from my home and there are two another mile or two away. In a relatively rural part of Southern NH.

Neighbors of mine just cleaned out one of theirs. Two years after moving. They were just lazy and didn't mind paying god knows how much when they had a barn they could move their junk into. Honestly, some people don't know how to get rid of stuff - or to simply not buy things they barely or never use.

Some things you cannot place in an unheated barn - and if you run a business, inventory can pile up. So storage spaces make sense. But the vast majority of people I know who have storage spaces never really do much more than just fill them and forget. The rest of us have barns that get filled with just tons of junk.