I bought two Springer books from Amazon that turned out to be print-on-demand. The font size and weight made them uncomfortable to read so I returned them.

I bought another self-published book that was also print-on-demand. The larger font size made it readable although the font weight makes the footnotes look quite bad.

I wish Amazon would show on the product listing that it's a print-on-demand book since they're inferior to traditionally printed books with the equipment currently being used.