My findings are that it's actually exactly the same. Peaberry beans occur in almost all coffee in some percentage. They aren't grown separate, they are the exact same coffee that's been sorted out of the processed beans so that the lot looks more homogeneous and sells better. I've actually been lucky enough to at one time have peaberry, oversized and "regular" beans all from the same lot. The coffees all tasted exactly the same to me. I have a friend that claimed he tasted some difference in in the larger beans, owing perhaps to not having been roasted as thoroughly.
The beans I had were Sumatran Toba Batak, sold in sorted lots of 17+, peaberry and regular. I am sure that almost any processing station you went to in the world could do such processing if they chose, although it's probably labor intensive and would add some cost to the beans. If Tanzania is doing it regularly, they have probably found it's financially worth it. On occasion when I look closely at the beans I am roasting, I'll usually find a few peaberries in the mix.