"But why does it matter if you bash a new or old car? End result is the same no?"
Well, what do you mean by "end result"?
End result of getting a largish scrape in an old car that already has multiple scrapes = resale value of the car will be reduced by a tiny percentage, perhaps a tenner, and annoyance factor will be minimal as you've already got multiple scrapes/dents so one more won't alter how 'nice' the car looks.
getting same sized scrape in a brand new car that was otherwise pristine = huge proportionate impact on potential resale value, likely up to several hundred, even thousands of pounds. Annoyance factor is huge as you have a pristine, lovely looking car apart from the scrape, which will annoy you every time you look at it.
I mean it's up to them, if they can afford it it's their money. I wouldn't do it, for the same reason as I don't like the idea of giving kids brand new iphones etc - if they get used to the best, top of the range thing as their first ever version, either they are going to have to keep getting the best ever version of everything for the rest of their life (which might be hard when they eventually have to start paying for stuff themselves), or they have to once they are no longer subsidised by the bank of mum and dad (or in this case grandma and grandad) and, rather than feeling the pride you get in buying your own stuff out of your own paycheque, just feel a bit crap because it's worse than your previous version.
I remember when I was growing up, we mainly had a primark/matalan budget for clothes. Topshop/Miss selfridge etc. was an occasional treat, but I looked forward to when I was working and could buy my own clothes at the 'nicer' places. My sister always talked about when she was working and could buy herself an Audi, etc.
Starting your first full time job can be exhausting, confusing, stressful etc. but the main payback is supposed to be that you have independence and more money to spend than you ever have before, to spend on treating yourself to things you've always wanted - if you only end up with the same, or even worse, level of 'stuff', what's the incentive? No wonder Gen Z hate the idea of 'adulting' = if they've been given the best versions of everything as kids then they only get the negative elements of paying their own way, and none of the benefits.