They really should. They're missing out.
On one of the last posts, I described the Snakebark Maple. How about another North American Native that has been overlooked? Indian Cherry. It displays lush foliage throughout the dog days of summer, and is laced with ornamental fruit when most other plants are tired and uninteresting. It deserves more credit than it gets!
Korean Mountain Ash is another virtual unknown. Most species of Mountain Ash are demanding customers, but the Korean is an exception. The clean flowers contrast with the dark foliage beautifully.
One final option- the Turkish Fir. Grand and stately with rich green foliage. I don't have a good photo of this one. You'll have to come out to the nursery and see it for yourself!