This work is currently or has been previously supported in part by the National Science Foundation (under awards CNS-0846065, CNS-1463968, CNS-1565252, CNS-1651230, CNS-2041894, IIS-1302709, Graduate Research Fellowships under Grants DGE-0718124 and DGE-1256082, and Computing Research Association for the CIFellows 2021 Project under Grant CNS-2127309), by Consumer Reports via a Digital Lab Fellowship, by the John S. and James L. Knight Foundation, by the UW Center for an Informed Public, by a Microsoft Research PhD Fellowship, by the Short-Dooley Professorship, and by the UW Tech Policy Lab (which receives support from: the William and Flora Hewlett Foundation, the John D. and Catherine T. MacArthur Foundation, Microsoft, and the Pierre and Pamela Omidyar Fund at the Silicon Valley Community Foundation).