One-in-five Australians regret not taking out private health insurance after being stung by an unexpected medical expense.A new survey by comparison website Finder has revealed 12 per cent of Australians felt the regret when faced with a minor health matter such as a dental visit, while seven per cent wished they had taken out cover after they were faced with a major health issue.Finder personal finance and insurance specialist Taylor Blackburn said a lack of insurance has forced some Australians