Human nature.
A good shadchan does a lot more than just present a name.
Hmmm… I don’t think so, unless someone acts as a central hub for that, such as NASI is doing for the older girls. (I think I’ve just answered your first question as well).
who will wait now till their 21 if it will cost them more this will just increase the problem.
No one’s intentionally waiting in any case (unless they are anyhow not ready).