Upvote:5
From several travelers I've met and spoken to (including when I was in Iguazu)...
If you're busing over the border to Cuidad de Este, the bus driver wouldn't even stop at the border. You can get dropped off in the city, and picked up again a couple of hours later when the bus comes back. It's a sort of 'we trust you' approach, it seems? Very odd.
However, travellers who wanted to go further (Asuncion), needed a visa. Go figure.
https://www.brendansadventures.com/how-not-to-get-into-paraguay/