This is an insurable risk. Airlines can either buy the appropriate insurance or take the risk onto their balance sheet.
The practical reality is that most travellers these days (particularly families) cannot afford the costs of a ten day delay getting home from the other side of the world, and don't have the time / knowledge to wade through the small print that allows an insurance company to avoid it's responsibilities.
Governments have decided that for the greater good airlines should manage this issue - and it is probably the cheapest and most expedient way for passengers to be protected.
The real issue is why airlines feel they don't need to comply with the law.