Earlier quoted context omitted.
Shoot, I accidentally reported the same income twice even with turbotax once because I didn't understand what non-covered shares were. (And in my defense, the broker also didn't show cost basis on the 1099-B either, I was just supposed to know)
I forget when the cost basis reporting requirements got firmed up but there were some point where I had options from a former employer that had gone through a couple rounds of acquisitions and when I eventually sold the shares I ended up throwing my hands up a plugged in some average cost basis that was somewhere in the ballpark and called it a day. It's all pretty automatic these days but it used to often be a real…
Cost basis reporting from the broker to the IRS is still blank for non-covered shares though, which leads to the other common case of "forgot a page of 1099, IRS thinks it's $0 cost basis, sends bill for $10k++, but actually you owe ~$0 if you send in the correct info".