It is not hard to understand why the government does not regard mugging as so serious a crime that it should always lead to a jail sentence, provided “minimal force” is used.
As the government have long made it clear that people should not defend their property with force against people who try to take it by force, they regard just handing your money and goods over as sensible and responsible behaviour. In short, they think the way to prevent violent crime is to stop people resisting and therefore remove the need for muggers to use actual violence rather than just the threat of it.
In other words, they want to make muggers more like tax collectors. Is that really so surprising?