I'm pretty sure Denmark has cooler temps than in Florida. For half the year, I'm dripping sweat just from walking 20 ft outside to the mailbox. The idea of wearing regular clothes to bike anywhere is absurd. I'd be a soggy mess. I wear cycling clothes when commuting to deal with the sweat. Fortunately I have showers at work. More employers need to provide showers.

Regarding not wearing helmets, I know someone who was just riding slowly down the sidewalk with his daughter. Fell over, hit his head, became a vegetable. Yes, not wearing a helmet can certainly kill you. You could probably make a similar argument for wearing a helmet when walking though.