Birmingplumb – are you seriously suggesting that a permit should be required to change a sink washer? If so, with all due respect: you’re insane. Or just want your profession to be protected by law from people who are smart enough to do the work themselves rather than hire a union parasite.
We can’t make everything 100% safe, and accidents will always happen. The water heater example is moot, since a permit/inspection is required in CA. What do you suggest to prevent DIY work? Only making plumbing parts available for sale to licensed tradesmen?