Fair enough, but I understood the point you were making in your earlier quote (as below) was that proving that full barrier crossings are clear before clearing signals for trains takes too long and leads to crossing misuse; Half barrier crossings are a different thing altogether.
With full barriers you don’t have the risk of motorists driving around them, sure, but you still have pedestrians, cyclists, diving under them to cross, and even motorists acquiring bad habits and thinking the long delay would also exist at half barrier crossings.
As far as I know, detectors expected to check that space between barriers is free have been tried in the past but have proven to be more troublesome than useful.
And finally, railway infrastructure companies like to standardize everything they can and probably won't find worth it to maintain a different interlocking system for the 1% of level crossing that have full barriers.
As a result of that, no such check is made, and it is even not guaranteed that the first train that arrives at a malfunctioning level crossing will be stopped before it by the lineside signals. Level crossing malfunction will bring the previous signals down, but the first train may very well be between the guarding signal and the level crossing already, thus with nothing that can still stop it in time.
