Generally speaking, people who give talks have them prepared beforehand. They practice speaking it, to make sure that it's clear and understandable. So to say that it's easy to write a transcript for a planned talk isn't really saying anything. It's already been written, and writing the transcript of the presentation is just a rewrite. Not all talks are prewritten, but almost all of the good ones are.

I'd also like to note that presentations are very dissimilar to conversations, and some interviews. Conversations are at least a two-directional flow of information (more directions with more people), whereas the bulk of presentations are a one-way flow of information.