Wee Brian,
Duty of care is a legal term, but I feel, as humans (disagree if you want) we have a moral duty of care to prevent people from death and injury as far as reasonably practical irrespective of their age!
You are right about compensation claims, but don't forget that if you injure someone, they might need care for the rest of their lives and this can be expensive.
Criminal law does not differentiate between young and old and mansalughter charges can be brough for killing anyone, a hotel group got fined £400,000 only a few weeks ago, a head teacher and local authority are about to get sentenced tommorrow. Death and injury is expensive, but even if it wasn't government, local authorities, fire brigades, fire prevention officers, building control, who ever you work for probably exists to protect life and health.