California passed a law that lets you rescue dogs from hot cars. The ‘Right to Rescue Act’ requires passersby to notify police if a dog is in danger- but, if the threat is immediate, you can break into a car to rescue the dog without fear of punishment– as long as you stick around to give the police a statement. Source
This law exists in most states for children too, and the dog version is probably going to spread or will be covered under the existing law for children.