When a group lists what is wrong and votes on what matters most, the winner is almost always the thing everyone can see: the waiting times, the outages, the complaints. Those are consequences. The causes sit further back, spread across people who each saw a different part.
True Causes lets the whole group find them. Everyone writes causes alone and unnamed. Then the group answers one question at a time: does this cause significantly influence that one? A link counts only when three quarters agree. What comes out is a map, deepest causes first, with every disagreement kept on it.
It works for a team of ten or a whole city: several groups can take the same question, each builds its own map, and the maps merge. People take part from their phone, at their own pace: a few effective hours in all, spread over days or taken in one sitting.