Currently, the enforcers posted outside of crime scenes are laughably ineffective at actually detecting when you enter or exit an active crime scene. Even a guard posted directly adjacent to a door will lack the cone of vision to spot you slipping inside, and even if they do see you in illegal territory they'll generally see it for such a short moment that they won't even become properly suspicious.
Making police tape rustle a bit as you move past it could provide a means of alerting a nearby guard enough to come at least give a half-hearted search when you pop in for a quick look-see. It would still be possible to duck into a hiding space until they lose interest, or cause a distraction that entices the guard to move far enough away from the entrance to not be alerted (or simply bypassing them entirely via vents), but these options then become actual rewards for gameplay and effort instead of simply being unnecessarily more-involved methods of the faster "ignore them completely and just walk inside".
Additionally, a slight rustle when crossing the threshold could provide another thematic punctuation of the thin line between the bloody chaos of a fresh crime scene, and the veneer of civil life just outside.