This has been the case for a decade at least. My understanding -- reading between the lines -- is that if someone has been to the US on a J1 they are more like

This has been the case for a decade at least. My understanding -- reading between the lines -- is that if someone has been to the US on a J1 they are more likely to return and work illegally. CBP screen based on this. It sucks, and has for a long time. I've not personally experienced any change post-Obama. The major variability is in the CBP agent, not in top-down policies. At the end of the day you have to choose between open and closed borders. If you want to close your borders then screening is a tough business. The main difference between the US and the rest of the world is scale and desirability. A lot of people want to go there, more than any other country in the world. That makes it difficult!