Do backlists actually generate any income?

We all know that to be successful in self-publishing fiction you have to release frequently - at least in most genres - and each new release drives sales and income. My question is do the backlists that you build up as a result also actually generate any significant income over time? It seems an important consideration if you are looking to create a sustainable business as an author. You would hope to create a flywheel effect where the stock of back titles creates a cushion of ongoing sales and takes some of the pressure off frequent new releases. However, when I look at the backlists of various authors on Amazon who have been self publishing for a long time they seem to have such low sales (based on the Kindle store rankings) as to be insignificant.

For example, Joseph R. Lallo from the Six Figures Author podcast (this is not a criticism of him and I think he is great, just that he is an available data point). He recently let it be known on the podcast that he was no longer a full time author and had taken up a day job again, so I think it is fair to say he has had challenges with sales in recent times like many authors. He has a backlist of about 60 books and I see rankings of the high hundreds of thousands for most, which I believe means sales of much less than a book a day and probably an annual income in the low five figures.

Is this an accurate take based on experience of those of you who've published for a while?