Why is it so hard to buy parts from people

I've recently had experience with both craigslist and meta marketplace. It is the same people or the same type of people on both. Like most, I do not want random people coming to my house. I've had two people back out of a deal because I wanted to meet at the local Home Depot, not my house. One person called that a red flag and backed out of the deal. At least, he didn't waste more of my time by flaking when I was at the Home Depot