An 80 year old, yes 80 year old, comes home to a burglary. Not exactly equipped physically to take them on is he? In a country of shoot first, ask questions later, then I'm not surprised. The US is also far more 'lenient' of such incidents and the right to defend one's property.
Having said that, it's California and my experience of Californian law is that they could well come up with some half-baked crimes on both sides..... The death penalty in the State has just been determined as unconstitutional by the way, 12 days ago actually.