There is no effective system of checks and balances, or this entire discussion would be moot. Civilian solutions(like ICEBlock and friends) are a whimper of a response compared to the lethal and aggressive actions of these LEOs. Typically entrenched groups(like LEOs) can not be talked or reasoned with into changing their position. Those changes in position come from leverage (ie, your supervisor is replaced or leveraged with the threat of replacement), or direct aggression.
As an example, certain villains took issue with these systems and mounted their own lethal response. We are /still/ talking about these individuals because of how riotously effective their actions were at illuminating and mitigating the perceived problems. Whether your talking about Ted K, or Timmy M....they are examples of people who took action to correct a perceived problem. Right or wrong, every reader of this post knows who they are, what they did, and why they did it. Until something of equal magnitude opposes the authoritarian problem of the day(ie ICE), the status quo will continue.
edit: typo
This is not a new force, they have no new powers. They didn't need to hire new people willing to perform these actions nor train them how to do so.
If you haven't considered this before it should hit you like a hammer to the forehead: where are the resignations? Where are the "good cops" we keep hearing about, what are they doing?
The other federal, state, and local law enforcement officers that are assisting in these actions, where is their principled refusal to violate their oath to uphold the constitution? What statements are their powerful and normally very vocal unions making about all this?