Gregory's Server@denschub When you want someone to trust you, it is the least convincing move to say: "you have to prove to me that I am not doing anything wrong."
Regarding DAP, read the first paragraph of the introduction of the spec. It states that you need to trust at least a part of the aggregators to "execute the protocol honestly". People have to trust (at least one of) the parties running the data-collecting servers.
Trust is essential for the entire argument.