Do any scientific publishers have a stated commitment to authors regarding copyright infringement?
Since you also ask for anecdotal evidence, I have a first hand experience with a commercial publisher (Wolters Kluwer) that reacted quickly and professionally to my message reporting prohibited commercial use of my work. This particular journal gives free access to articles after a one year embargo.

An internet magazine based in India copied verbatim large parts of the introduction and abstract of one of my papers with some words in between to try to make it look like an original journalistic report. The 'article' was available for a fee.

Since I formally transferred my rights to the publisher in the author agreement, I really only reported the issue out of interest for the outcome. They took contact with the 'company' that subsequently retracted the content from their website. 

I suspect established publishers like Wolters Kluwer have significantly more legal firepower than a one-person operation run from an internet cafe in Hyderabad.