Sale barns are in business to make money. If they feel THEY (not you) can make more money by selling "all black" cattle then that is their right and choice. But that doesn't mean you have to play their game. Go elsewhere, as suggested above.
The Angus folks have done an excellent job of marketing. Just excellent. They have convinced a lot of consumers that Angus beef is some how better than XXX beef. If you note the requirements for Certified Angus Beef, the rules say it just has to be 51% Angus.
You sale barn is not even saying that, as I read your post. They are NOT saying it has to be Angus or even 51% Angus, they are saying they just have to be "Black". I assume this is because they can then be passed off as "Angus" beef even though it is not. You can have a lot of full black cattle of different breeds with little or even NO Angus in them. You can bet these will somehow be labeled as "Black Angus" beef by the time they get to the store.
Tyson does have a big program on now called "Star Ranch" Angus beef in the stores and labeled as "produce of the USA". They have evidently found people responding to this program. I see it even at my local grocery store - here is a photo:
This is a photo from my phone I took when shopping with my wife recently. This is a smaller local grocery store in a medium size town in Illinois. Apologies for the quality of the photo. Frankly the beef looked great. From what I understand from the store staff, this program is working. The beef looks great and folks are buying more of it. The price is not much higher than the obviously lower quality stuff they are phasing out.
This is marketing! And I think that no matter what breed we raise, we should applaud anything that increases the consumers interest in beef of any kind. And especially beef raised in the US (apologies to Canadian, Australian and others...).
There has been a lot of cheap (to produce, not at the meat counter) lower quality beef sold at meat counters in recent years that frankly may turn folks off to beef in general.
I applaud this marketing move by Tyson and the Angus folks. I think it is up to us Hereford folks and others to step up to the plate and market our products as well.
In the end, I think your local sale barn is responding to consumer interest in purchasing quality beef that they know where it comes from. That is a good thing for beef producers in general. The fact the Angus folks have figured out a way to tie into this trend is a smart move on their part. The rest of us just need to step up our efforts to raise and MARKET quality beef, not just pounds... I see your sale barns efforts as a positive point for beef in general. jmho
Jim