LAFORGE: They're wild in some ways, actually puritanical in others. Neat as pins, ultra-lawful, and make love at the drop of a hat.
I wonder why that didn't raise any red-flags for Picard and Riker.
Presumably because multiple people reviewed the data the Federation had on the Edo, and none of them found any major downside like "executes all criminals." Which means the Edo didn't share that information with the Federation in the first place.
Doesn't seem like anyone even asked what type of punishment system the Edo had, in the event one of the crew inadvertently broke a law. They were too excited to get down to the horny planet.