Basically: We don't know if telepathy really exists. Since we don't know if it exists, there's no reason why we should have developed a way to measure how fast it works. We don't have all the facts about how the universe itself works. Maybe we will discover how to make FTL technology happen. I hope we will. But for now, such a technology remains a part of science fiction, and as long as it's applied consistently within whatever setting uses it, I'm content to suspend my disbelief.