I'm pro-bike, but this issue also applies to having a bike repaired at a decent workshop.
Our daughter's hand-me-down bike (previously "owned" by both her elder brothers in turn) had new brakes and brake cables fitted recently, and the repair bill was the best part of €150.
The equivalent job of replacing all of the brake lines and brakes on a car would be a multi-hour job with several hundred in parts alone. By comparison, having a competent mechanic completely overhaul and inspect the most critical safety system on a bike for €150 seems like a pretty good deal.
Absolutely, and I was happy to pay for the brakes to be sorted!
€150 is a fairly substantial repair cost relative to the new cost; remember that this is a child's bike suitable for an 8-10 year-old.
Having all the brakes replaced on a car might well cost thousands, but cars cost tens of thousands new.
In that case, if you bought a top of the line racing bicycle for the child, it would be a much lower proportional cost for the brakes! (joking of course)