I think a lot of the problem is not feedstore assistants etc trying to deceive customers, they just often don't know a whole lot about chickens. Also if the hatchery sells them something different than what they ordered, they often won't pick up on it because they only deal with chicks once a year and probably aren't all that interested in them. When they are misinformed, they pass that on to their customers and so it goes.
If I was in charge of say plumbing parts, i'd probably mislead a whole bunch of people too just because it's not something I know anything about or am remotely interested in. We do have one assistant at our local feedstore who knows a lot about poultry, but that is because his father raised birds. Nobody else could tell you more than what's a duckling, what's a chick and what's a gosling. They do all swear up and down you can sex them by picking them up by their head, waterfowl included, but i'm not fighting that losing battle! They mostly see the chicks as a big headache each year.