It depends on case to case. Landowners can be held liable for injuries on the playground if they do not inspect, repair, or remove any known or discoverable hazard within a reasonable time. Suppose repair or removal is impossible or impractical. In that case, landowners are required to provide an adequate warning of hazards on the premises in the form of Playground Warning Signs, unless the general scope of the risk would be open and obvious through the reasonable use of one’s senses. However, injuries due to obvious hazards like falling from heights would not be considered a fault of the landowner. The specific laws surrounding playgrounds differ by state, and you should consult a local lawyer to know who is liable.