If I can say something radical in a slightly different direction, I don’t know why “professional” Shadchanim need to exist at all. I have a friend who was single. My sister had a friend who was single. I knew enough about this girl because my sister spoke about her and had her over a few times, so I set it up. They got engaged, and I was quite shocked to receive a sizable check from the new couple. I didn’t do it for money, it just seemed right. And apparently it’s quite rude to attempt to refuse the money (I asked both the Chassan and Kallah individually because I really felt very uncomfortable taking their parents’ money). So I just bought them a really, really expensive wedding present. It was my money and I could do what I wanted with it.
The point is, people in Frum communities know people. You don’t need boys knowing girls well or vice versa. You need guys who know guys and girls who know girls, and then the overlaps (siblings, close families, neighbors, friendly parents, etc.) can set people up. Honestly, I think turning Shidduchim into a big business has hurt single people more than anything else.