As we grow, we experience society evils everyday (grow each day). With Gurdwara management type of folks, most are born and raised in India and experienced high caliber of corruption, cheat, dishonesty and they end up with distrust attitude.
People change after the interaction with certain type of folks. If someone stiffed them over money for an example, he/she will end up trusting less in other fellow humans.
Above is why our Guru jee said that no matter what, live a truthful life.