Many small businesses don't adhere to professional norms of communication, negotiation, payment, etc -- that's not a big surprise, considering that many of them are owned by people without a lot of background in big business. The amount of time put into each deal is very high compared to the money you can get out of it.
This is why enterprise sales are so much easier than small business sales. You can make millions dealing with a small handful of enterprise companies, or you can try to make the same amount of money by dealing with hundreds or thousands of small businesses.