They do not have to continually opt-out. The opt-out is one time, it is online and it takes less than 5 minutes to fill out. Google couldn't make this process easier.
The problem is, will this sort of 'agreement without authority' extend to other parties? That is what I mean by continual opt-out. Continually having to reaffirm to someone else that you do not want them to distribute your work on your behalf - just remaining silent should be enough.
I know what you are thinking "They shouldn't have to opt-out at all".
If the book is older and the copyright owner is unknown then there is a chance that person is dead. What now? Perhaps the heirs will claim the work, or there may not be any heirs. If not, the book is lost. The only way to find a copy of it will be to travel to a library that has a physical copy. Once that physical copy deteriorates, gets destroyed, or stolen, then it is gone forever. To me, it seems like a terrible trade-off to protect the copyrights of people who are too lazy to spend 5 minutes to protect their own works.
Well, firstly Google is digitising these works, so they have to have a physical copy to begin with - so the book is not 'lost', you just have to wait out the copyright expiration before you can distribute new copies of it.
There is nothing stopping Google from storing the physical copy until then, or even digitising the work *now* and storing both for a future date. But no, what they want to do is circumvent copyright and release the works *now*, for profit.
You can look at a home with an IR camera and figure out other stuff -- like if they have any strange heat sources that suggest illegal grow operations
And how would you be able to determine whether or not what they were growing was illegal? I've seriously thought of growing tomatos in my basement because the ones you buy at the grocery taste like cardboard, but fear of the War On (some) Drugs keeps me from doing it.
We grow orchids in our basement under high pressure sodium lights, and have never been bothered by the police. None of the other members of our orchid society have encountered problems, either.
Exercise your rights! If you live in constant fear of the police state, they've already won.
Today's scientific question is: What in the world is electricity? And where does it go after it leaves the toaster? -- Dave Barry, "What is Electricity?"