pre blog

Will someone please explain the overuse of "pre"?
How do I pre-book? Does this mean I'll still have to book but perhaps pre-booking means I'll have a better chance. Pre-enter, well, either I enter or not and if I enter before entries open, what's the point.
I fully expect someone to ask me to pre-reserve a place at the restaurant, but perhaps if I pre-book my table I'll be able to eat my meal and leave before I actually have to book.??