The store is called All-Saints Spitalfields, and it's not limited to Seattle. That's a British clothing chain and every single one of their stores--Seattle, Las Vegas, New York, et cetera--are all decorated the same way, with tons of vintage machines on those racks.
I'd heard (but never been able to find direct print evidence) that the owner of the chain has a bad case of SMAD and practically cleared out the UK secondhand sewing machine market to stock the store displays worldwide.
The All-Saints store near me in New York also has, on the floor, some impressive and gigantic 19th-century Singer industrial sewing machines that are the size of motorcycles. Just staggering to see in person.