[shangxiao]

Incidentally most of them _are_ focusable by the keyboard but just aren't tabbable.

I'm using a Chrome plugin Vimium - one of the shortcuts 'f' (documented as opening links) actually highlights all focusable elements. Using this feature shows most of the checkboxes are interactive.

Edit: I guess the reason for me pointing this out is hopefully there's an easy way to make these more accessible for keyboard users.