system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do better car brakes improve braking?

Brakes in pretty much all maintained cars (even with cheap brakes) are strong enough to be able to lock all wheels on dry surface while putting the pedal to the floor - at least from my experience. The car doesn't need to be a new one. 
If that's the case then how does installing better brakes actually improve the braking?
gpt
Bigger pads and rotors can slow a wheel to a stop faster, although that’s not necessarily the goal.

When discussing performance *brakes* you have to remember that they’re being fitted to a performance *car*.

This isn’t 25mph gently down to 0mph at a suburban stop sign - it’s 125mph violently down to 55mph coming into turn 6.  Then back up to 132mph down the back straight.  Then heavy braking into the hairpin, which you’ll take in second gear.  On sticky slick tires that don’t lock up easily.

The brakes are going to do this over and over and over, with mere seconds to cool off between push-you-into-the-seatbelts stops.  Heat buildup is intense.  At higher tiers of racing it’s common to see the brake rotors glowing red hot through corners.

Your typical road car brakes aren’t built for this, and they’ll warp or fade quickly under the abuse.  If you plan to make a fast car stop, you need something designed to handle the heat and the incredible traction of racing tires.