Well, I might be wrong so feel free to correct me since I'm new to BPs. I've seen normals being handed out like candy at expos before and the ones that are on tables are no questions asked $5-15 purchases.
If folks just hand them out to whomever because they need to move them due to lack of rack space they will more often then not end up in the hands of people who will not treat them right.
I've seen this plenty of times with leopard geckos and crested geckos, folks would almost rather pay the replacement cost of $5-25 for the geckos instead of say....actually keeping them in proper conditions so they wouldn't die.
It is much less likely that someone will abuse a snake that is more expensive. Who pays for say a Killer Spinner at $3500 and then treats it terrible, no one. Also, you aren't hard pressed to clear out your rack of Killer Spinners so you can take the time to make sure the person your selling to knows their stuff.