I live on a horse farm and as a result, need to buy hay. Our main "hay guy" is a farmer and his son who lives about 1/2 hour away, has great prices and charges a low fee (usually: sometimes he doesn't bother charging) for delivery. There are online hay markets, and Craigslist.
They don't bother with any of that. They just ask us to tell other horse owners about them so they have a market. When I drop by to pickup some hay, they are almost never there: I leave cash in the mailbox. If I don't have exact change and I overpay by $5, he gives it to me the next time.
There are many, many, many people who are perfectly happy doing business like this. They like their work, make enough money at it (going by the shiny new tractors!), and have no desire to get online or grow their business.
I have more anecdotes about other similar people I've dealt with just this week alone, but you get my point: many of these markets aren't remotely large enough to interest a VC and the participants only want to do business face to face.