Speaking as a biologist working in Australia: 1) Older collaborators with more power are being 'scared' of getting scooped when they post preprints. They're sl

Speaking as a biologist working in Australia: 1) Older collaborators with more power are being 'scared' of getting scooped when they post preprints. They're slowly coming around as the argument makes no real sense, preprint = published to the younger generation. 2) Funding bodies, i.e. the people who pay our bills and have all the power. The Australian Research Council, the biggest non-medical funding body here, does not allow mentions of preprints in grant applications. They give no reason for that rule. 3) Again, money. You want your research to go into the journal with the highest impact factor since that mostly decides whether you get to keep your job, get that new position, or get that grant. Some journals still don't allow preprints. You also get no feedback when a top journal rejects your paper, could the rejection be because others have seen your preprint, published papers built on top of the preprint, and now your paper submitted to the journal is not so novel any more? You have no way of telling. 4) Fear. Sometimes, after your paper has undergone peer review it's a little bit better. A few select people see the embarrassing errors in your paper and help you fix them before the paper is widely accessible. If you post a preprint the world sees your glaring errors.