I still dislike the practice, but my apologies for the more curt earlier comment. My assumption was that the practice was indeed your own. I had maybe confounded registry with registrar. That said, in general terms, who would these registry partners be for unclaimed domains, who then set elevated "premium" prices?

The underlying TLD holder.

Usually all dictionary words, domains below 3chars, domains below 4chars, etc.

Right, I meant on their part