Why is it so hard to buy parts from people

People always talk about craigslist flakes but that's always assumed that it's the people buying stuff.. it's the same with people selling stuff... I don't go to marketplace too much or I guess it's Facebook I use my wife's phone for that but I find no difference.. generally I find the same exact stuff for sale on both..
On craigslist I generally asked to have them email me a phone number and a name and that right there weeds out many many flakes...
The recently put a vehicle for sale and had the fifth guy in line ask if he could be put first giving me the old my son would like it also and I don't have a vehicle line...
Needless to say that took him completely out of the running...
Personally I just took near two tons to the scrap yard last month and at least 80% of it could have been sold but dealing with people... Not interested... Between Ferris and non-ferrous I got about $750..
I needed one of the six radiator fan blades that I scrapped the following week...
:BangHead:... It cost me 20 bucks from a really good Mopar guy that sells parts close by... That $750 is now $730 lol and until I spend all that on things I could have kept I'm still feeling good about not having two tons of scrap metal around... Or some people put it parts I could use one day...