I can think of no possible justification for leaving a giant hunk of personal property completely blocking a sidewalk. Regardless of the legality, if you leave such a thing around a blind corner where children are freely allowed to ride bicycles, related damages are on your own head.

How about a discussion with the car owner regarding a bit of common sense and situational awareness? Perhaps the child should sue said car owner for endangering her. Unreasonable? Shall we leave chunks of debris on roads around such corners?