The purpose of a brake van on a passenger train is to provide a handbrake to secure the train when no locomotive is attached or coupled. Individual coaches in the UK don't have handbrakes, so would only rely on the automatic brake to secure the vehicle. Of course as explained earlier, the auto brake can leak off sometimes with tragic consequences.
There's a Belgin Vicinal line I work on that does not have continuous brakes, but each passenger coach "should" have a serre frien, brake man, to apply the hand brake in emergency. Line speed is limited to 15 km/h. I understand some form of continuous brake is being fitted to enable line speed to be rained to 25km/h.
As for fitted goods wagons, very few if any existed when light railways were introduced and it remained that way until the railways converted to air brakes and banned unfitted trains.