I see what you mean, http://www.wikitree.com/genealogy/Millett lists 80 but that's definitely not 80.
This is probably one of our cases where the number is misstated. The problem is described here: http://www.wikitree.com/wiki/Cutting_costs#Surname_Counts
I wouldn't expect this with a surname with so few people, though. There may be a bug we need to investigate.