Your argument is flawed and stupid. My cousin claimed she WANTED to drive but couldn't afford it
You did not say this in your original post. You simply said she said she couldn't afford it, not that she WANTED to but couldn't. If she'd rather smoke than learn, it's pretty obvious to me she did NOT want to after all. Perhaps she said that just to end the discussion. Actions, not words!
She, like many others who can't drive/won't drive, constantly scrounges lifts off us drivers though
Your cousin sounds cheeky. I hope you don't give her free lifts as it will only encourage her, but you know that, right? 
And you can't have applied for many decent jobs, if you have NEVER applied for one that requires driving as a skill
Define a "decent" job? I have been perfectly happy with my jobs up to and including my current favourite. The commute is a dream - I work from home. 
With the cost of trains now, (and the time it takes for some journeys!) it's ridiculous to travel by train when you can drive
Is it really? I'd rather read a book during that time than spend time stuck on the roads. Freedom of choice - it's a wonderful thing!
Me and my husband and 2 kids wanted to go to Edinburgh several years ago; from where we lived, it would have cost us £380 return for all 4. It cost us £65 return in petrol. I have many more examples... where the 4 of us travelling by train costs 5 or 6 times MORE than the cost of the petrol in the car! And it's often faster. Sometimes the car journey is HALF the train journey, and you are not affected by strikes, late trains, no seats, and restricted times back home
Seems you've made the right choice for you and your family. Well done you!
Also, it's almost impossible to cope without a car, when you have an actual JOB, and kids at different schools (that are in opposite directions to where you live, and both at least 5 miles away!)
My life works perfectly well for ME, thanks.
It's OK to not drive if you have zero responsibilities, and no kids
It's OK not to drive if you don't want to. No-one's permission needed!
You can afford to be a 'I care about the environment' hipster then
I don't care about the environment that much, actually. Shame on me! It is a legitimate reason for some not to drive though.
When you have a job, your kids go to different schools, you have elderly parents to care for, and you live in a village with lousy public transport, let's see how your 'I DON'T DRIVE' bollocks pans out then
My life without driving is panning out beautifully. Don't your elderly parents drive then? I guess that will happen to most drivers eventually - oh dear!