Dog owners should know this (and NOT to leave dogs in hot cars), but sometimes new dog owners are not as educated or aware as they should be.
I also wish that florists had warning notices on plants and flowers that are toxic to animals. So many bouquets contain lilies, for example.
I tried to keep catnip around for my cats so they would leave the other plants alone. I was aware that dogs paws are sensitive and would never trust a dog to keep his paws off a hot pavement. After all if they are walking with you they will bear just about anything to prove their love.