What went wrong in Sweden? I genuinely don't understand that. The news keeps showing Swedes walking in parks and down streets, but that's not how people catch

What went wrong in Sweden? I genuinely don't understand that. The news keeps showing Swedes walking in parks and down streets, but that's not how people catch the novel coronavirus. Meanwhile, people were working from home and mass gatherings were banned; the public were trusted to figure out the details, but they're not idiots. It could have worked. What was everyone doing in Sweden that people weren't doing in Finland and Australia? Or were there less visible differences, in surveillance and contact tracing maybe, that haven't been so widely reported?