Part of the problem as I see it is that it is now possible to evade modern barriers with ease, and then cross the track. Even easier with half barriers - just walk round the ends.Then, on top of that, the trespasser will unconciously assume that crossing the railway is just like crossing the road - road traffic runs at slower speeds and drivers can, to some degree, evade obstacles. In addition, pedestrians recognise road vehicles, understand what they are, what they might do, how they sound. The front end of a fast-moving train has a different and unfamiliar set of visual and audio cues, so once you've jumped the barrier, embarked on your journey across, that distant image of the front of a train is NOT going to approach like, say, Occaido's van. But unconciously you think it will. Bang! And there's an element of bravado - "Watch me, folks, I'm real cool and can easily get across - oops! - that was close, and I've lost my shoe". Only your shoe, pal - lucky!
When I was a little boy we used to go down to the level crossing at Brierfield. The signal-box was right there, next to the road. The signalman looked out, up and down the road, then pulled some levers which lowered the gate stops. Then he would wind a big wheel and the gates closed across the road, all the time with the road in view. Another lever locked them there, and yet another locked the little pedestrian wicket gate in the closed position. All the gates were substantial structures, robust, weighty, and would have been awkward to climb over, if one was crazy enough to try, right there under the eye of the signalman. But modern barriers are flimsy by comparison, there is no signalman, just (if you're lucky) a camera on a pole and an observer miles away, who might be doing other things - certainly not taking a look up and down the road before winding a big wheel. Why did we do away with the big gates? Are they too expensive to work? - to maintain? Or just "not trendy" enough old technology must go! type of thing. It looks to me (but I have no calibrations for this) that the modern barrier, its machinery, the TV, the associated track-circuitry and wot-not would come close to the cost of maintaining the man and the signal box and the big gates.