Just because someone gets themselves into trouble, does not guarantee they will be rescued - it never has and it never will - you need the crew, the aircraft and the weather to perform the rescue.
The Captain of the aircraft is responsible for the safety of his aircraft and crew over and above that of the casualty and there will always be some situations where the risk to life of the crew outweighs the enormous will and desire to rescue the casualty.
Talk of unacceptable waits for rescue is pointless - someone who is bobbing in a raft (unless with a life threatening injury) is a far lower priority than someone clinging to a rockface who is a lower priority than someone being swept away in the dark by flood water.
Unless you want hundreds of helicopters ready to rescue everyone all the time, you will never give absolute certainty but, by the time you add in the RNLI, the Coastguard ground units, the mountain rescue organisations, the police, fire and ambulance crews and the many volunteers out there, the UK provides a fairly comprehensive safety net for those in trouble.