you're assuming, that open access journals need a handling fee
distribution costs are marginal, it is possible for an open access journal that wouldn't take handling fees. it could be a non-profit organisation, or it could have other monetisation methods.
Yes, I'm making that 'assumption' because the article says, "... open-access journals, such as PLoS ONE, which charge authors a handling fee to cover their operating costs ..."
EDIT: Link from comment above shows fees for the PLoS family of journals start at $1350 per article and go up rapidly from there.
I absolutely agree. The pay-for-publishing model is heavily disadvantaging towards smaller research institutions, independent researchers or young researchers.
distribution costs are marginal, it is possible for an open access journal that wouldn't take handling fees. it could be a non-profit organisation, or it could have other monetisation methods.