Sibling commented on organizational disadvantages that may or may not be inherent to cooperatives.
However, another explanation is that the dominant economic and legal environment - and, indeed, society itself - is structured around a single business model: the capitalist as chief, and workers with no meaningful voice in management.
Mondragon emerged in a region with strong traditions of industrial organization, communal solidarity and popular education, as well as a recent memory of workers' movements. It also arose within living memory of the large-scale worker collectivizations of the Spanish Revolution, particularly in Catalonia.
Much of the social and institutional environment that has made this possible has weakened over recent decades. This was not merely an accidental development: in much of the world, it was the result of a conscious political project that accelerated in the 1980s.