Trying to format table rows with alternating backgrounds (or generally: alternating row formats), I realized that It's *very hard* to do:
The only way to do it seems to be using "auto format" of tables, so I tried it.
However none of the predefined formats did fir my needs, so I wondered:
How does "auto format" actually work? Unfortunately you cannot "edit" any of the pre-existing autoformat templates, and when adding a custom autoformat, it simply copies the existing table format (it seems).

So I tried applying a pre-existing "auto format" to my table, then inspecting the formats to see how it is done (to be able to modify it before saving it as my new "auto format").  However I was not able to find the magic that implements the format assigned, not even in macros.

In contrast considering current HTML and CSS, it's rather easy to do it there:
table tbody tr:nth-of-type(even) { background-color: #ccc }
(Assign a different background color to all even table rows that make the "body" of a table)

I think Writer should have similar possibilities: For rows and for columns.
Autoformat as it is now may be a nice idea, but the current implementation is close to being useless.