I didn’t click through to see Amazon’s internals. If you are sufficiently interested, the link is in the source article.
When Amazon reports financials, they do not release the number of Kindles sold. IIRC, they report Kindle revenue as a whole, which includes e-ink units as well as the Fire.
Btw, I own an e-ink kindle. Some things are good for uni-tasking. Plus, I can switch between the kindle and the kindle app on my iPad and the last page read is synced between units.