Modern Home Made Controllers. (D.C.)

[Mountain Goat]

I don't pretend to know a lot about this, but I have seen people on Youtube and on these forums I am on making their own controllers from pre-assembled elsctronic bits and pieces which may have something to do with Ardurilo? (If I am right and have spelt it right).
Basically some sort of readymade speed controller circuit board?

Anyway. With my qestion. They never seem to include some sort of short circult protection as they claim they do not need it. Why isn't it needed as without a means to prevent a direct short won't it destroy sensitive components or even a transformer (Though I think these act as a transformer via electrical componenets?)
Anyway. I am puzzled in how one can get away without a form of protection. Doesn't the track or the wire melt during a short or the motor damage if the controller doesn't need any protection and therefore one has not added any?

Maybe someone can answer. I am not pretending to know a lot, but what I do know is I once came across a friends old Triang controller which had a dodgy overload protection button so it melted and did not allow the overload to trip, and his 12v wiring was glowing red hot. A day or two after he said the controller blew up, so I knew when young the importance that overload protection does for train control if there is a short, as even if it does not destroy anything the controller end, this lesson was that it can potentially set low voltage cables on fire. So I don't see how one can get away with no form of circuit protection with these modern "Home made" (Home assembled) devices.
Maybe someone can answer who knows how these things react during a short, and I am only asking out of curiosity.

[Viscount]

I have made controllers using the Arduino Nano processor. The output from the Arduino feeds to the track via an "H-Bridge driver" which raises the voltage from 5V to track level, provides more than sufficient current and critically will trip out if the current drawn exceeds a defined level; to reset the over-current condition, the power must be removed and restored. I would also add that most "switched mode" power supplies (to take 240VAC to a low level DC) also have overload protection built in and will ceases outputting if presented with a short circuit (or over current load).

Hope this helps.