Surely the 4th amendment is technically "directory" to public officials, not mandatory?

Under Illinois law at least, that's how it would be interpreted, since the US Constitution lacks any punishment for violation of its terms. [0]

The exclusion of evidence is a judge-made remedy for something that doesn't exist in writing, and for most of the history of the 4th amendment it didn't exist.

[0] https://www.isba.org/committees/governmentlawyers/newsletter...