It is a real problem I agree, cats have a significant impact on smaller/song bird populations. On the other hand, they don't cost the taxpayer billions of dollars or trash entire landscapes.. and they do serve some useful purpose for some people.
both of course kill vastly more birds every year than all the oil spills in the history of the industry combined
Windfarms neither costs billions in tax-dollars... Austin gets energy from a privately-owned windfarm... If you are suggesting they got some sort of tax deduction because they were building a windfarm, then I'd ask you to apply your dislike for tax deductions to everyone you like along with the things you don't like. I can name several favorable tax treatments oil companies are able to take advantage of... But I'm betting you don't count that as "costing the taxpayer billions of dollars."
Also... "trash entire landscapes" is an entirely aesthetic preference. It doesn't actually trash the landscape, you just don't like how it looks, which is too bad for you I guess, since people with private property are allowed to trash the landscape in all kinds of manner without your consent.
Thirdly, you are suggesting if 300k birds die, this is bad, but if literally a million times more birds than that die, that's totally acceptable as long as people get the "useful purpose" of having a cat... the useful purpose here being complete unbeknownst to me. What is the useful purpose of having a cat? One old lady is slightly less lonely? What is the useful purpose of having a wind-farm? It generates electricity for way cheaper than the alternatives, far less pollution is caused by it than the alternatives, and also, it only kills 1 cat for every 4+ million that die so that grandma can be less lonely.