I can’t provide a generic answer but in my experience, there were two mechanisms. First, people are hired partly based on their political values and through word of mouth, which limits ways for bad actors to join. In the same vein, the pay is below market-rates, which reinforces the phenomenon of ideological homogeneity. Second, decisions are made through consensus using formalized methods. Frequent meetings that are prepared in advance following a set of rules, disagreements that are discussed using techniques that minimize the subjective dimension of it and are solution-oriented, elections without a candidate (in French: “élection sans candidat”), etc.