This seems like a straw man, but maybe this really is how some utilitarians think. My view is: if the cost in terms of trust lost is greater than the expected benefit of an action, then the utilitarian answer is not to do it. If the only way to prevent a "race to zero trust" is to make some bright line rules and enforce them universally, then that's the utilitarian answer. It's literally impossible for another ethical system to reliably provide greater total utility than utilitarianism, because utilitarianism is the rule that you do whatever leads to the greatest utility.