You should have to ask permission to track someone with Locator bar.

It feels incredibly Invasive to know that anyone can track you at any time. Well there is ways to prevent this by wearing a carved pumpkin or mob head, No one wants to be wearing these all the time. It's also a disadvantage to be wearing these and not a helmet that has protection and enchantments. I know this is a toggleable Feature. But I feel like most Servers will choose to keep this on to take advantage of the new way points that can be created. And well I think this is a useful tool. I also think it can be Heavily abused. You have now given griefers a guaranteed way to find victims. 

I think a simple solution to this is to have it so if someone can right click a person with A compass that person will then have a screen appear in front of them saying, Do you agree to being tracked by this person. That person can then choose whether or not they will be tracked by that person. People's right to be tracked or not should be respected. Even if it's in a video game.