I understand that this is a bit unusual in the US.
Maybe 20-30 years ago, but certainly not unusual now.
White eggs are still more common, probably because they're so cheap - those eggs cost me $4US, and I can get regular white eggs (minus all the certifications) for $.99.
Brown eggs, though, have always been available and not unheard of. There was a time when brown eggs were considered stronger in flavor (and not in a good way) and higher in cholesterol, and (believe it or not) not as "fashionable" as white eggs; like, if you were eating brown eggs, you were looked on as some kind of rural hick who had to make do with low quality brown eggs, while good, upstanding folks had nice pristine white eggs. We had brown eggs when we had chickens growing up, and I hated when Mom put one in my lunch, because I knew I was going to get teased/bullied over it.
Now it's kind of flipped, and brown eggs are considered a bit elitist, and blue/green eggs...you're a downright snob if you have those (and I can get blue/green eggs at my local small-town Kroger for...wait for it...$7 a dozen).
I care less about the shell and more about the innards, but I buy those because they're certified humane. If I'm eating an egg, I want to know the chickens haven't had their beaks lopped off first, piled atop one another, and all the other crap they do to chickens on larger factory farms.
When I have more time, I buy them from a farmer around the corner from the house, and the difference is amazing. The eggs from the farmer, I just about need a chisel to get the shells cracked and the yolk is some shade past deep orange. The extra-cheap white eggs are incredibly fragile (I've broken more than one just holding it in my hand) and the yolks are barely pale yellow.
