Because people live here and are telling you that a tornado watch can sometimes be a weekly occurrence in the summer. Tornado warnings are far more rare, but even then, it generally takes tornado sirens/phone alerts to adjust people's behavior.
As far as yesterday was concerned, Edwardsville (and neighboring areas) knew they were in the line of fire by 8PM local time. The tornado hit the facility at ~8:40.
Things can get out of control quicker (15-20 minutes warning is usually as close as it gets), but I think it's definitely reasonable to suspect negligence in this instance. There are two possibilities, imo:
1. They had enough time to get people to shelter, and chose not to
2. The facility wasn't up to par
