why is _taxonomynode_get_nid_from_tid private?

It seems to me this would be a useful function to expose to other modules, but it is declared as private with an opening underscore.

As long as this module exists you'll need a function to retrieve nid based on tid, so why not set this up as an api function other modules can use? Otherwise, I'm forced to dig around in the database (coupling my code to taxonomy node's implementation in a much worse way) or use taxonomy's api to awkwardly extrapolate the right tid.