It's largely because they aren't made by Trek, Specialized or Dorel. That's not a snarky answer either, BTW.

The dealer agreements really restrict what secondary and tertiary lines a dealer can carry. It's not so much that they're told what lines they can and cannot carry, (although that's been known to happen), but that they have minimum purchase and stocking requirements with the primary brand.

Unless the dealer is located in a high population center, or already does mega business with the primary brand, they really can't afford to stock such a boutique brand.