The stores around here have them side or top cut.
I just started seeing the top cut ones a couple of years ago.
I kind of like them better because both sides are the same thickness and the goodies you add don’t fall out...
When we visit Judy’s brother over in Sarasota on Lido Key. He always takes us to the old casino on Sundays for New England lobster rolls. They have them on sale on Sundays. The buns are top cut, and boy are they good!!