I wonder about this though because cars are “fragile” due to being designed to protect the humans inside. I would think that the sentient cars would have evolved differently to be more protective of themselves.

Nah, that’s what CATS named all of us

For real. The concept of becoming a master over a wand is world breaking in retrospect. Ron talks about using a hand-me-down wand in the first book, which basically means he was hampered from the beginning by not having a wand that recognized him as its master. And all the wand disarming Harry did means he should have approximately 37 wands that prefer him over their owners.