I was also a bit careful. In my week away from home, I managed to horde away the equivalent of $10 Canadian. I did so by ensuring everything I bought was as cheap as possible. My per diems were small, but my expenditures were smaller. I need that $10, and I do not feel that my actions were particularly dishonest—even though, in the end, this $10 which used to be somebody else's is now mine.
But hold on. Am I not rich? I am a mzungu; my potential wealth has no limit. If I, the mzungu, am strapped enough for cash that I will only go to a training if there is a per diem attached, imagine what Tanzanians will do.
Thus is born the per diem culture: for any formal business meeting and for any training, per diems are expected. Pay-offs vary wildly, and attendance depends on the pay-offs.
Now, flip the coin over and picture this from an organizer's perspective. A meeting is hard enough to organize: to find a time and venue which works for all attendees, to prepare the topics of conversation, and so on. Throw these per diems into the mix: an organizer in Tanzania must determine how much each attendee will need. Are you training teachers? Are you discussing policy with government officials? Are you inviting journalists to a press conference? These cost money. If you bid too high, you waste money. If you bid too low, you could be shunned. You may advertise the fare before the event occurs, but actual attendance will only be revealed at the beginning of the meeting. (Or, because the culture encourages tardiness as well, an hour after the meeting begins.)
In the West, we attend meetings and trainings with the aim of accomplishing things. In Tanzania, a seemingly thoughtful concept (helping to cover expenditures) has been inflamed to the point of insanity.