The police are accountable to elected officials. If there is the sort of significant abuse this comment thread is full of, there will be popular outcry.
The futility of protests and outraged posts on social news sites is nought to do with democracy. The police are popular with the majority of Americans (This is a post about a US city), and so if a minority of people object to tools police use it is futile.
HN is rife with police hate and outrage but we have a very professional police force filled with good people who do a good job protecting our security. If you doubt it, try other countries that don't have what we have.
It's the libertarian streak of the average HN reader. If there's anything inconsistent it's the libertarian who wants personal freedom to the extreme but also a quality of life they are used to in a western democracy.
First you say that democracy means we have nothing to fear from police with drones, then you imply it's pointless to resist because the democratic methods don't work.