It’s a whitewash it’s to launder the guys work clothes who work...

It’s a whitewash

it’s to launder the guys work clothes who work inside the gold room. Normally have to strip off to your undies in an outer anteroom, walk through a “ security “ section where you are searched under camera, then inside the gold room where you change into working clothes. And the reverse on the way out. The work clothes never leave the gold room.
Much harder to steal gold this way.
not much fun for the people working there.
Normally a shower and toilet inside as well, and often a crib room so only one entry and exit per shift