Well, I didn't want to mention tastytrade as some people say I'm biased. But since you did..
I have no idea why they do what they do. Presenting results in dollar terms is completely meaningless. Even if you backtest the same stock over 5 years period, and the stock price doubled, which probably caused the typical straddle price to change significantly as well. So if 5 years ago the straddle price was $10 and today it's $20, how does it help to compare the dollar P/L? it's comparing apples to oranges. Even on the same stock.