Thank you for the opportunity to help you with your question!
Ducks have the mentality of most birds i.e they are only afraid of humans or animals standing on two legs or four legs. As such, to them, cars aren't dangerous hence they can cross the streets in search for food on the other side without caring to let the traffic lessen first. And the ducklings always follow the mother duck wherever the mother duck goes.
Please let me know if you need any clarification. I'm always happy to answer your questions.