I'm only one person.

And who says that the buffer could only be for a Tin Man? There might be a community of giants who favor armor close enough for the buffer to be a necessity.

No one ever freaks out when the foursome shows up; it's a land where magic is common. Who knows how many animate metal folks arrive on a daily basis.

Also, look at Manhattan. It's not that big an island. But even if you only look below 14th Street, you'll find two unused subway stations. If Manhattan can support two unsued subway stations, Oz can support at least a dozen giant buffers.

Wall mounted can openers were a thing, my grandma had one, and it had a decorated back plate too with 60's style orange and brown flowers printed on it.

Scarecrow's table right next to it is identical. Hopefully they put some kind of cushioning on them for clients not made out of tin or straw.