lol, "high quality tea bags." That's an oxymoron. For example, try real Longjing tea, and then try tea bags sold as being Longjing tea. The tea bag teas are routinely over-fired or under-fired, which is why they are used for tea bags in the first place (low quality).
Try those green teas sometime and look at the color of the tea liquor. You will find that it is light brown, not green like a proper whole leaf green tea. The flavor of tea bag green teas also tends toward flat, burnt, bitter, or grassy.
The tea industry is not stupid. There is a sophisticated market, and the top teas are sold for top prices. The shitty inferior quality leaves are chopped up into fish food and sold in tea bags. Sorry, but that includes "Costco" brand as well as others such as Tazo. In the end, even if you are paying up to $10 for a box of tea, the quality of the leaves is still pretty poor, because you have several big businesses making money on that measly $10 little box of who-knows-what.
In general, westerners are stupid and naive about tea, and western companies are cheated constantly by the Chinese tea market. It's sufficient to say that the Chinese keep all the good tea for their own market (which has consumers who might actually know their head from their ass, or at least insist on seeing the actual tea leaves to judge their quality).
https://www.teaguardian.com/category/quality-varieties/tea-varieties/black-tea-varieties/
After I came back from China the first time, I couldn't find decent quality anywhere. The worst are the teas being sold to Chinese immigrant communities in America. Pretty much all supermarket teas are trash, and even brands like Tazo are usually pretty bad. I ended up importing from mainland China, and eventually from a seller in Hong Kong who is a tea expert (and has better teas in general). I've tried just about every brand of green tea tea bags I could get my hands on including many from Chinese companies (and I spent a shit ton of money on it just about every week with online orders and trips to other cities even). In retrospect, the only ones I would consider to be "good" were whole-leaf tea bags that generally cost more, and are found in some Asian markets in North America. As for ones that are "acceptable," Tazo has China Green Tips that is okay, and Foojoy has a "Bai Mudan" that is okay. I know about teas and ratings, and I've written dozens of reviews myself on the most popular site for that, but if you get into those sites enough, you will see that the top reviewers always say something like, "This is actually not shit quality for a tea bag," because they already know that whole tea leaves are better quality than fish-food flakes of low quality leaves. They set the bar low for tea bags.