I think that you need to approve a tag that somebody puts on you, because you don't want someone to invade your privacy. You might have taken that picture without thinking that it would be put up online. Someone else also might tag you in a picture that you are not in.
I do not believe people should be allowed to tag others in Google or Facebook photos without the others person's consent. Allowing this would open up a window for potential abuse. When employers look over social media sites to make hiring decisions, the chances of abuse to these sites needs to be reduced as much as possible.
No, I do not believe that a person should be able to be tagged in a photo without their consent. In some cases people tag a photo just to get the attention of a large amount of people. There should be a notification if a person is tagging you in a photo and it should not be allowed until the tagged person has authorized the action.
As someone who's not on Facebook or similar social media like Google+, I'm sure my photo is nevertheless posted through other accounts, and probably tagged with my name. Because these sites are collecting information about people, photos really should only be posted when all the people in the photos have given their consent. It would especially be wrong to post photos of children on these sorts of websites.
People unfortunately have no current way to prevent photos of them, even compromising ones, from showing up on the Internet. However, they can at least have some level of plausible deniability on Google and Facebook if the pictures are not attributed to them. Unfortunately, the default privacy settings on Facebook actually allow these photographs to be tagged by others.