A nit but still a good point.

However, I believe Trek do manufacture their higher end bikes themselves in Wisconsin. At least they did a few years ago when I toured their factory where they were clearly manufacturing bikes.

These alliances do all add value though. Azor is a bike manufacturer in The Netherlands. Here's a great video of the process: https://www.youtube.com/watch?v=RdY3DcW4oFw

Workcycles is a 'manufacturer' in Amsterdam though they might better fit your marketer definition. Henry Cutler the owner of Workcycles is a very good design engineer. Originally he resold Azor designed and built bikes under the Workcycles brand (actually Henry Workcycles for a short time). He then designed slightly lighter and sportier versions of the Omafiets and Opafiets that Azor then built and he sold as Secret Service. Azor soon licensed these and also began selling them under their name. Workcycles then designed the Fr8 & Gr8 bicycles that are manufactured by Azor and sold by both companies. More recently Workcycles have designed (after some 5 years and dozens of trials frames) the Kr8 which is an improved version of the Bakfiets.NL.

Both companies add considerable value, both benefit from their relationship, and customers benefit.

On a side note, Tesla builds a mean car. And I think they manufacture a higher percentage of their branded car themselves than any other car company.