If a firmware update exists, its probably too technically challenging for Joe User to find and install. For a lot of these devices, there isn't even a published fix. These manufacturers are just rebranding some generic camera from a larger manufacturer or using the same camera and IoT guts and putting them into different cases. These companies probably don't even have a software developer on staff who has access to these firmwares, just perhaps a binary blob, assuming they have any software people on staff at all.