You've been severely misinformed. You can read for example the UK's pre-pandemic playbook at (https://assets.publishing.service.gov.uk/government/uploads/...) - note they specifically call out universal masking, border closures, and restrictions on public gatherings as bad policies they don't plan to implement because there's no good evidence they help. Maybe they were wrong (I definitely think they were wrong on masks!), or maybe the difference between true influenza and a coronavirus with similar symptoms matters, but it's just not accurate to present these kinds of policies as the pre-pandemic consensus.