"The nineteen fifty two ... Southern service to ... Brighton ... is delayed by approximately ... twelve ... minutes due to ... trespassers-on-the-railway. Please listen for further announcements. We apologize for the inconvenience."
(Replace with "a passenger taken ill on a train" or "action by the police".)
"The train approaching platform ... two ... is the ... delayed ... nineteen fifty-two ... Southern ... service to ... Brighton ... calling at ... Clapham Junction, East Croydon, Gatwick Airport, Haywards Heath and Brighton. This train has ... twelve ... coaches. Platform ... two ... for the nineteen fifty-two service to ... Brighton."
I much prefer it to a live announcement. The slightly ... odd pauses are distinctive, but mean derivations from the usual announcement stand out, whilst the whole thing is soporific for commuters. For others, there's the much-needed repetition of the most important bits; the destination of the train is spoken three times.
Examples: https://youtu.be/0cg-n-GF38E?t=139 (At 3:20 there's a Welsh one!)
(I don't like the repeated keep-your-luggage announcements, but maybe they're justified since people are still trying to bomb railways with abandoned luggage.)
But on a station it is possible to only put people in front of the mike who speak accent-free German and English, and to properly adjust and maintain the amps, speakers and wiring.
But also, I disagree with the failure rate of 90+%, from my experience I'd say it works pretty well in 90+% of the time. The system can even announce the "umgekehrte Wagenreihung" ;)
The pronunciation of city names is also rather lacking in many instances, and like you say often doesn't match the surrounding speech.
Before the privatization attempts, the Deutsche Bahn used real announcers on the major train stations.
Now, after decades of cost-cutting, it's pre-recorded audio pieces played by a computer. They sound broken and mismatching (because it's no TTS engine), they fail to be played half the time (and frequent rail users would claim the failure rate at 90%+) and of course the stuff breaks down when something unexpected happens (like emergency rail closures, due to people on the rails, med emergencies, police action, ...).