A growing share of market will follow from continuing business with many individuals. When you receive an Email message or response form then it must be acknowledged immediately, and if this is an auto-response then there must be a human response the same day or sooner. Many websites fail on this and they probably, and well deserve to, lose the business. Best is a product that can be delivered over the Internet. It costs nothing to duplicate, and nothing to deliver, and there is not much lost except for your reputation if it screws up.
Service products require time, and no one has any time.
And there is a lot of spinning of wheels before you can ask the customer to pay. You may have to make a house call, and an earlier date is better than one next month. In this case the immediate objective is to get the appointment. Then it is down to you, eyeball to eyeball, to clinch the sale. Solid products have to be delivered.