Golden retrievers were bred for their ability to control their jaws/bite strength better than other breeds, they know how to control their jaws so that they aren't hurting or damaging anything they carry in their jaws, they were mainly used to retrieve birds and other small animals for their hunting masters.

My dad and i used to play fight a lot when i was a kid, and my golden retriever would always come to my side and give him warning bites on his arm to give me the winning edge.

HWALG