It's all about price point. the components all have price points.
they buy pallets of cases of components but Shimano has no favored bike company pricing.

so at the given price point, the component choices are going to be more similar than different.

A Cannondale CX ultra is only sold by a Cannondale dealer
and distributors only let dealers sell a particular brand of bike
in a market area that will be far enough away to not have them close to each other.

another brand of type and price-point will likely have the same sort of mix of parts.

[small print .. prices and specifications are subject to change without notice]