The idea of fuck cars isn't to make drivers lives worse but to make everyone who can't drive for any number of reasons (age, finances, anxieties and other disabilities, etc) have access to an equitable life.

My brother has crippling anxiety behind the wheel. He's tried driving and physically cannot do it without putting his life and the lives of those around him in danger. Should his life be worse, or should he be subjected to only living in dense metro areas his whole life because of this? Or should he have a viable transportation option no matter where he lives?

That's the real idea behind fuck cars. Unfortunately when people with so much are asked to share with people with little to nothing, they see it as an attack on their freedom (which only goes one way) rather than a equalization of the playing field.