"That's not accurate. Skilled workers built those."

The skilled workers did the difficult parts. Getting the materials to the construction site and other (often dangerous) tasks were done either by children or peasants that had either been forced or attracted by false promises. In addition the churches and kings often didn't pay the promised money. Just read some history books. The top guys always wanted to keep as much to themselves as they could. No difference to now. They could be even greedier back then because the little guy had no rights.