Of course, this should never have been taken with a straight face by the media as it is wholly implausible. You have to have a “free and fair” count and reporting of the count to have a free and fair election.
Tanzania is one of five EAC member states (and the one with the most stabile recent democratic progress, but a ruling party that has not turned over since independence). Groups of diplomats from the EAC and SADC are not similarly situated to outside, at least notionally independent, observation organizations.
See: How is IGAD’s “diplomatic observation” regarding Kenya’s election process helpful? from February 1, 2013.
Election Observation: Diplomacy or Assistance? from July 25, 2010.
Here is the link to the EU Election Observation Mission which issued a positive but temperate preliminary statement on the progress of the election yesterday. There are always “real world” issues and limitations, but these EOM’s are institutionally established to have some level of bona fide independence, and the government facing this election is not a member of the EU which includes many members with a wide range of relevant interests.