Just encourage people to upload their paper to an open access archive like arXiv first. Very few journals disallow this, it's just that authors are either too lazy or just don't want to make their paper publicly available.
Yeah same in some fields of Physics, for example all theoretical stuff, along with most optical or optomechanical stuff is always on the arXiv, however for example some obscure paper on seismic noise might only be in some very expensive journal
