It's a double standard based on the fact that free-roaming dogs can and do kill people and livestock as well as wildlife, while free-roaming cats are considered more of a nuisance from a human standpoint despite the fact that they are the main carriers of toxoplasmosis (which recent research reveals is a more insidious disease than we imagined) and also vectors for various other parasites and diseases such as rabies.
And yes, free-roaming cats (pet and feral) have driven some rare species to extinction and threaten vulnerable populations of more common ones. Among the earliest examples are the dodos, those icons of extinction whose nests and young were easy pickings for the cats sailors and settlers introduced to their islands, but plenty of modern species are at risk, including birds, reptiles, and amphibians. Cats take food out of the mouths of native predators such as foxes, weasels, hawks, and owls and even threaten the existence of wild felines species by competition and interbreeding.
Unfortunately, with every step conservationists and wildlife lovers take to apply the same standards of responsibility for care to both dogs and cats, there's an outcry from a small but fanatical faction of cat "lovers." I put that in quotes because if they really loved cats they'd want them to be safe indoors or in outside enclosures, not on their own eating wildlife and garbage, getting killed by cars and dogs and tortured by sadistic people, and suffering from a huge list of diseases including Feline Immunodeficiency Virus and Feline Leukemia Virus. The average free-roaming cat lives less than one third as long as one that's not allowed outdoors unsupervised.
The Great Outdoors Is No Place For Cats
Impacts of domestic cats on wildlife welfare and conservation
Cats and Wildlife: A Conservation Dilemma
Domestic Cat Predation on Birds and Other Wildlife
The Impact of Cats on Galapagos
The effect of feral cats on the population viability of black-vented shearwaters (Puffinus opisthomelas) on Natividad Island, Mexico
Stephens Island Wren (driven to extinction by cats)
How the Macquarie Island Parakeet became extinct