In this scene, Queenie just walked out of MACUSA with a briefcase full of people evading the law. And clearly somebody had to walk into the building with the briefcase. Switching the briefcase to muggle mode won't help here.
Surely the guards know briefcases might be bigger on the inside than the outside.
When briefly stopped, and somebody asks what she is carrying, she answers vaguely, "Ladies things. Do you want to take a look? I don't mind." Sure, she could have used a transfiguration spell to alter the appearance of items, but a good guard would simply use the revelio spell to show what's really there.
But what I am asking about is not this one particular moment in the movie, but the general policies of guards in magical government buildings.
Why didn't the guards search the briefcase? And for that matter, why not search every handbag, wallet, shirt pocket, and anything else that can hide stuff? In real life, we can't go through airport security without being searched, so wouldn't sensitive government buildings in the magical world also require searches?
Is there any reference in any canon sources about guards at magical places searching people's carriable property?