Many lithium batteries have failed while being used exactly in the manner prescribed, because of either poor engineering or poor quality control driven by cost concerns of the manufacturer.
And many have failed while being used exactly in the manner prescribed, despite proper engineering and great quality control. It doesn't matter what the manufacturer of a device using lithium batteries does, if you sell enough of them you WILL have some of them explode and/or catch fire even if everything was done right.
A can of gas isn't "stored properly" if it is in your living room. There's a reason why it has recommendations for storage, filling and usage, and despite all that STILL would be against every building and fire code to store in it in your living room. Because it is known to be dangerous. Fortunately we don't use gasoline powered appliances so there is no reason to have gasoline in your living space, but no such luck with lithium batteries.
One has to wonder that if we had known of their issues before they appeared on the scene if consumer safety legislation wouldn't have banned them for use in devices intended be held in the hands or used in the home. I'd still have my lithium battery powered hedge trimmer that's stored in the garage, but my iPhone would use something else and probably be twice as thick.