From my years in working retail at a women’s clothing store…it’s because the basics just don’t get the buyer all excited. I managed to grab her one time and tell her, “Look, we could have ALL the plus-sized dealers shopping here regularly if we could just stock B&W clothes consistently!” This was in Las Vegas, where most of the casinos wanted their dealers to wear plain black pants and equally plain white shirts. The buyer agreed to try to find a steady source, but apparently she couldn’t, or wouldn’t.
A big part of the problem is that a trendy item will usually sell in a couple of weeks, while a basic item will languish on the rack for a season or two, sometimes.
I STILL think that our store would have done well to have set up a little “Black & White” section, or a “Basics” section, and kept it well stocked. But then, I was only assistant manager, and not buyer.
I have a Ralph Lauren shirt here just as you describe, but the sleeves are too short on me, due to my ape like arms so I have now replaced it with a new one with longer sleeves.
If it will fit you I’ll happily send it off. It’s nice - 100% cotton.