Because Bianchi is an actual bike company that's been existence for a very long time. Motobacane used to be a bike company but they went out of business.

BD bought the rights to the Motobecane name and sells bikes under that brand to fool people into thinking that they are getting a brand name bike at a huge discount. In reality the list price they give is a total fabrication and the bikes have no historical connection with the Motobecanes of old other than the name.

And really that's my biggest gripe with BD. For the price I think you get a good value. But this whole business of selling under defunct brands and advertising savings of 60% is so phony. Just create some new brands and quit lying about the sale prices.