When you have a family of 40lb raccoons in your yard...they can cause problems that any dogs would be proud of. There must me a set of 2 latches that have 2 mechanisms on them in order to open. could be as simple as a latch with a caribiner (D ring) passing thru a hole. etc.
Our cans are the property of the trash company so we can't modify them - you'd think in rural areas the trash company would get locking lids of some kind for their rural customers!!!!!