Many many fewer precincts and political domains. The US has a total of 3,143 counties or equivalents per Wikipedia, obviously divided between 50 states and D.C

Many many fewer precincts and political domains. The US has a total of 3,143 counties or equivalents per Wikipedia, obviously divided between 50 states and D.C., each a separate political domain, both counties and states. Corrupting enough of those under the Electoral College's constraints is a lot harder.