You can still deal with the old bright bulb cameras: you can have rules which apply to everyone. So you can make a rule at the park that pictures are allowed, but only without flash, or that only digital cameras are allowed, or only digital cameras with the fake-shutter noises turned off, etc. As long as the rule applies to everyone equally, it's fair, even if you think the rule is silly.
For websites, it's not fair to have different rules for Google than others. What would be fair is some kind of rule about how often visitors can visit, how much they're allowed to download, etc.
Personally, though, I think all this is total BS. Sites are open to the public, but they also serve the whims of their owners. If the site wants to prevent access to people from a certain IP range, that should be their right. If they don't want any scrapers, that should be their right too, or if they want to allow Google and not anyone else, that should also be their right. What isn't right is that they can use the government to enforce these arbitrary rules. If they want to block my scraper, that's fine, if they can do it on their end technologically. If they want to block my IP, they can do that too. But suing me or having the cops come to my door because they're too incompetent or lazy to do these things technologically is unacceptable. The role of government is not to enforce arbitrary policies made up by business owners.