Ebook publishers are, for the most part, existing publishers of paper books and are maybe not savvy on how to design for computer use. While creating a hyperlinked index can seem a tedious task it can be automated.

I tried it with a song book I'd created myself, using Open Office and setting up the contents page so it was hyperlinked to the individual songs. It wasn't difficult but when I tried saving as html, there was so much extraneous formatting tags that it would have taken forever to reduce it to a manageable level. Most ebook formats are based on html under the bonnet but elaborate formatting isn't needed for the most part. I convert individual songs to mobi format for my Kindle with a very limited number of tags and it works well.

With the song book I mentioned earlier which was a book of songs with notation and chords for the ukulele, it looks as if the publishers have not really thought it through. The notation is as images but they are not scaleable, even on my android phone which will happily scale pdf files so they can't be enlarged for easier reading. The contents/index page looks as if it's a single image. I suspect the publishers have done a "quick and dirty" job which does not do justice to the possibilities of ebooks.

As to the paper version of the New Penguin book of English Folk songs, the paper seems quite good quality but it's true it isn't as opaque as it might be and you can see what's on the other side faintly. Also some of the page cutting is a bit awry, but nevertheless it's worth every penny.