In England there are lots of shared pedestrian and cycle paths

In Vietnam all paths are shared pedestrians and motorcycle paths, whether intended or not. Every day I am on both sides of the equation. I have never hit a pedestrian or been hit as a pedestrian except someone going the wrong way on a 1-way. Been hit by bikes on my bike half dozen times, a car once.

As a pedestrian, I’ve had to jump out of the way more than once, and was sorely tempted to take down one rider who got dangerously close on a narrow trail, despite having ample room to go around if he’d wanted to.

Either you're afraid of bikes and overreacting by panicking infront of people who are going around you or english bikers are uniquely unskilled and anti-social. It could genuinely be either, but the way to solve this is to get all sides to be more predictable.

Better to assign strict liability in any pedestrian/motorised vehicle collision to the driver of the vehicle

Is it not already like that? Here nobody calls the police because it creates a headache for everybody, but its generally understood motorcycles have a responsibility not to injure pedestrians.