There could be many charges bought as a result of an RTA, it absolutely relies on the circumstances.I don’t recollect that being involved in an RTA was ever in itself a disciplinary offence; the charge was always one of negligence?
What did change was the burden of proof. Summary dealings for stuff like RTA, losing an ID card etc etc weren’t exactly fair trials in the 90s and earlier.
You are spot on with the "burden of proof" thing and, like anything else, RTAs had to be properly investigated. Which, as you intimate, they hardly ever were.
But AGAI action became an easy option, and continued the ability to nail an individual without a proper investigation.