@algo a lot of people think that children are very vulnerable in trailers. I am not aware of any evidence for this. Many people probably mean "the child looks quite vulnerable"'but it comes out as "that is wrong"?
I have an early Tagalong in my garage that is a pole with a BMX bike stuck on. The hitch was rigid and made steering tricky. I only ever took it on the WoL path as when I was trundling it home down viewforth some kids ran out from between parked cars and knocked me off. This put me off going on the roads with that particular device but modern trailers are much better designed.