Did you get a weisswurst instead? Germans will refer to weisswurst as bratwurst.
Good point, many do not realize just how generic the name "Bratwurst" really is. We have been conditioned to believe that Bratwurst in the US is a single specific type of sausage. Translated into English it simply means chopped meat (Brat) Sausage (wurst). There is also a correlation with Brat and Braten which means to roast.
With the name Opa's, which is the German word for "Granddad" I would assume they are probably not using a "generic" brat recipe of the US, but maybe leaning toward a traditional German version of bratwurst.
Many of us in the US have only had exposure to the more popular Americanized version of "brats" as we call them. They are great sausages, but when we become confronted with different types of actual German Style Bratwurst, we are unable to understand the many differences, in texture, spices, types of meat, as well as different diameters and sizes. They just don't fit our version of what we envision Bratwurst to be. The same holds true with the generic Polish word for sausage; Kielbasa.
There are many different types of bratwurst from different regions in Germany. German cooking sites list over 40 different varieties of German Bratwurst. Some made from a meat slurry like our hot dogs, while others are made from an extremely coarse ground meat.
Fränkische Bratwurst
Coburger Bratwurst
Kulmbacher Bratwurst
Nürnberger Bratwurst
Würzburger Bratwurst
Winzerbratwurst
Thüringer Rostbratwurst
Nordhessische Bratwurst
Rote Wurst
Yet the generic term "Bratwurst" in Germany also includes;
Blood sausage
Bockwurst
Braadworst
Currywurst
Regensburger Wurst
Frankfurter Würstchen
Knackwurst
Knockwurst
Leberkäse
Teawurst
Weisswurst
Wienerwurst
Wollwurst
Even in Germany what we call Hot dogs, and Kielbasa are considered Bratwurst.
One of the main issues is that some varieties are meant to be grilled, some are meant to be pan fried, others are meant to be oven roasted, while some are only meant to be boiled. Then there are the specialty brats like Coburger which is meant to be roasted over burning pinecones, and Teawurst which is slowly simmered in tea. Not cooking them in the style that they are meant to be cooked in, will result in a different taste then they were designed.
While I will eat Johnsonville Bratwurst, I'll take a traditional German Sausage from our German butcher over the generic brats available at the grocery store any day.