Even on Star Trek, there are many civilizations that decline to join "the club". Star Trek is silly anyway, because it is unlikely that so many civilizations would reach nearly the exact same degree of development at exactly the same time.
Is it though? Star Trek depicts a universe teeming with life, and in that context there will be numerous civilizations at pretty much every level of advancement possible. They show that in the series too: many episodes revolve around an incredibly advanced or primitive civilization, or even talks about distant past civilizations long since gone.
Also, as we learn more and more about physics, we get more and more confirmation that FTL communication/travel is fundamentally impossible. It is highly unlikely that interstellar travel will ever be like taking the train to work.
FTL travel is just the classic exception that allows sci-fi to work. Without it, just about everything in Trek would be impossible, but nowhere does Trek imply that this will happen. Instead, Trek is "assuming this is possible, what could happen?"
"Spock, did you see the looks on their faces?" "Yes, Captain, a sort of vacant contentment."