Because person A, who evades paying their taxes, is agreeing to pay those taxes as their contribution to society, and then dishonestly and illegally trying to avoid that responsibility.
Person B, who's relying on government support, is being supported by their peers in exactly the way we've collectively agreed that people in need should be supported.
So yes, Person A is a far more dishonest and reprehensible individual. They're literally the only one doing anything wrong.