I'd be interested in knowing what percentage of the Hidden Champions are publicly traded companies. Companies of that size are very likely to be acquired in the US. Consolidation is a constant activity by many public firms and probably (I am speculating) tends to reduce the proportion of mid-tier companies relative to Germany.

Once acquired, these companies have an additional set of factors weighing on them in that the founding team is likely to leave, budgets are controlled by, and, profits are sent to an external firm. Those three factors will reduce the company's ability to determine it's own fate.