Not a "stupid" way to do business at all. The store clerks are adhering to company policy and could lose their jobs over giving a customer more than they asked for. The corporate world is a beast sometimes, but it's all about bottom-line profit. Please don't blame the staff. They are only doing what their employer requires them to do--meaning Hancock's, Joann's etc. Not sure about LQS's but their profit margin is much lower, so I assume they need to be extra careful.
If I need to pay for an extra inch or two, that's fine with me. I've been shorted a couple of inches on muslin for a backing and my quilt was ruined, so I get extra to compensate for "human error".