You have a lot less to prove to CBP than someone coming from a broken country. Your incentives to stay in the US are drastically less than someone from, say Mexico. Other countries do the same thing. A US citizen gets a warm welcome into Mexico. A Guatemalan gets hassled.

There's still random bad luck - as a Canadian I've been theatened deportation for not cancelling my green card despite not using it or living in the US. I've been detained because a CBP agent decided a trade show was work and I wasn't eligible for a B1. (His first words were "you're going miss your flight, I'll make sure of it".) But most of the time they wave me right by.