You, unfortunately, don't understand how Traxxas operates in this matter. They don't just require a ship to purchase "a few units"...they require the shops to purchase large quantities. Just to give one example,v when a new vehicle is released, of the street price is above a certain dollar amount, shops are required to purchase a minimum of one of each color...and, for vehicles below that price point, they are required to purchase more of each color. If I remember correctly, when the 4Tec 3.0 Corvette was released, shops had to purchase at least 3 of each color. This wasn't 'optional'...it was a 'requirement'. Put another way, in how Traxxas deals with LHSs, they don't just act like an "800lb gorilla"...it's more like an "8,000lb gorilla". And, if a shop doesn't want to purchase the minimum number of units Traxxas is requiring, Traxxas removes them from being an authorized Traxxas.
Look at it from a distribution perspective. Horizon Hobby is a huge company (much larger than Traxxas), with several brands names under their ownership. As such, they operate their own distribution network. With the exception of Traxxas, all other RC companies, large & small, use other distribution networks. Traxxas, on the other hand, handles their own distribution. Why? One could say, it's too "save money on distribution costs"...and, if you don't look any deeper, you'd be at least partially correct. But, if you DO look deeper, that's when you discover the strongarm-like tactics that Traxxas uses. Is it legal? Possibly (I'm not a BAR-certified lawyer...plus, my areas of legal knowledge are landlord-tenant rights, and employee rights). But, is it 'right'? Definitely not.