For most people, it'll be returned as they leave.
For people who really shouldn't be there, it serves as a filter; If they can't afford to loan the US $250, it is unlikely they will be able to afford theirlife necessities once in the US. Such a person should solve their issues BEFORE traveling to the US.
For visa overstayers, it funds their deportation.
What is clear is the bias of the article.
The US administration would have to be extremely incompetent to not be able to organize this much. Yet the article pushes this idea.
So, family of four saves up to visit NYC for vacation, now they need to find an extra $1000 to take the trip. And it's unclear when they get that money back (is DHS going to post somebody at international departure terminals to issue them - unlikely).
We can argue what the amount should be, but that's a separate discussion.