Because it's lodged with the cardrooms company when they do their taxes - this is also how most people get done for wellfare fraud and alike. They work while getting x government assistance, then the company they work for files their taxes, your name/email/address/creditcard are filed and a few days later some IRS person gets your name on their desk going "why aren't we getting money from x person, says here they should be giving us x". Then you get a knock on your door.
So yeah. Don't try and avoid your taxes. Anybody that pays you money has to do taxes too, and as a company, they will 100% file. You'll only end up hurting yourself.
