Silly Kathy. Vendors use heavy blues because they run heavy blue lighting. It's hard to filter that out for an accurate representation of what the coral will look like in your tank since they're likely running almost pure blue in the "farm" and we're running closer to 14,000K typically.
Depending on the vendor though, they can get very close to what it will look like in your tank, most just don't take the time to work the picture or if they do, they make it too fake.