A while back, a local Witness lost their home in a fire. An announcement was made at the meeting that if anybody wanted to contribute, they could do so through their service group overseer. My guess is that this arrangement is meant to bring tears of joy to the eyes of the impoverished one, and thankfulness to "Jehovah's Organization." Just a faceless handful of money from Jehovah.
it seems to me that a person should know who their friends really are when there is a crisis. "Taking up a collection" is fine in some circumstances but why would you want to make a person feel that they are out of harmony with God's "arrangement" if they simply offer to help privately?