I imagine the government could use this to make political profiles of people and eventually deny entry to or harass those they feel do not uphold the beliefs and values of the country in question, even if they have no criminal record or previous run-ins with border security
Well then you've obviously never seen the inner workings of a government. The government is made up of a bunch of people, just like you and me, who really aren't that interested for the most part in their jobs. They go to work, play on the internet, answer a phone call here and there, and go home, whereupon they try and forget that they have to work for a living at all. And then they retire. Trust me, it isn't the government monitoring your movements on yahoo. It might be Yahoo - they'd be far better at it - or it might be a global ring of organized criminals. But it's definitely not the government.
