As stated pretty clearly, he had to make the special tool. Every car I've ever owned or worked on you could either just use a flat headed screwdriver to drive the caliper back, or just use a C-clamp
Well, you basically 'made' a special tool by using a G-clamp. Similarly, you can use the end of a large (20-24mm IIRC) R/OE spanner to turn the piston in.
I guess I don't see the advantage. Why should I care if the handbrake is a disc or not?
Some examples would be that you don't require a separate drum brake just for the handbrake, and that you can safely use the brake to stop the car in an emergency without worrying about the all too common self actuation that happens with dedicated handbrake drum systems. Also, drum brakes are almost useless in dirty conditions, as they fill up with crap and wear out in a matter of a few hundred km (even when the brake is not used).
NONE of those have required make/model specific tools to do routine maintenance tasks like setting the valve clearances, or changing brakes.
None of the examples of special tools I gave are actually required, you can always find something to do the job fine. You'll probably find that all those manufacturers recommend special tools in the FSM, just no one actually uses them.
Who said anything about racing?
No one did, but the GP was rather obviously referring to turning in a situation where a loss of traction is to be expected, which implies a racing situation, an emergency, or an idiot driver. I chose to use the term 'racing speed' to cover these, I agree it's pretty ambiguous. Regardless, my point stands -- every car handles differently under loss of traction, and to manage this various 'tricks' can be used. Knowing these tricks for your own car can make a huge difference when it comes to avoiding an accident.