The short answer is that Curie sets the follow % for the vote trail, and then it is up to the sub-community curation teams how they use their votes. Some sub-communities e.g. #steemstem are much more conscientious in parsing out their vote power, giving large enough % votes that the Curie follow vote is still meaningful. Other sub-communities have decided to spread their vote % out far and wide; the mechanics of a trailing vote necessarily mean that if you are trailing a vote at a reduced %, and the original vote is actually cast at a low % to begin with, the trailing vote is going to be tiny. The bigger point here is that each sub-community's operations are independent from Curie. Curie has set the cap for total vote % of the follow, but the sub-communities have freedom to determine how to best use it. Some of decided to opt for spreading it out to a very large # of recipients, even if that means the reward going out to each is quite small.