Any competent, reputable company providing 30 year warranties in marine environments is going to stick test panels in a temperature-cycling salt mist chamber for an appropriate amount of time.
From first hand experience, the warranties on PV panels aren't all they are made out to be. For one, manufacturing runs of many panel models last months. after, while the warranty will be honoured, you won't be receiving identical panels either electrically or cosmetically. Worse still is when the equivalent offered has different dimensions.
The warranty itself is good but doesn't account for practical considerations especially when you are working with a component that's part of a larger whole.
These articles tend to be generous with interpretations of their poorly cited sources. Still, without knowing where the early PV systems are in the US, it's a difficult claim to back up. There is also survivorship bias and the fact that quality control on small batches of any product is usually better than on mass market stuff.
After the section you referred to, the article goes on to claim that poor regulatory oversight is responsible for the short lifespan of Australian PV systems... again, a questionable claim.
Do you have concrete data for this or are you going off manufacturer claims? To the best of my knowledge - and i work in the industry - the vast majority of rooftop or domestic PV installations are under ten years old. Some of the oldest ones that were mass-installed are in Germany.
I highly doubt PV panels will last 20+ years under most environmental conditions.
Also, before you compare PV lifetimes between the USA and australia, bear in mind that the great majority of Australian installations are very close to salt water. That plays havoc with anything installed outdoors, particularly metals and glass.