Is the trust naive? Have there been instances of a government violating that trust? Were they held accountable?

The US was a much higher trust society before repeated governments from opposing parties violated that trust with little or no consequences. This left people with no realistic competitive party that was trustworthy, and first past the poles elections ensures they only have to be slightly less despicable than their opponent. This also drives polarization.

Having a multiple party system with something approximating proportional representation, an independent press and judiciary, and a smaller population and land area all make a large difference. The US was the last nation to use first past the poles for something besides a house of commons that was ranked a democracy by vdem I think? Definitely the last one to be ranked a full democracy. The largest remaining population ranked as a full democracy is Japan, it doesn't look too likely to change from the outside. Germany is next in size and we'll see how that goes. SK was next and they passed a rough test so lets hope. Large populations are easier to polarize apparently? I wonder if that will hold true with social media eroding the rural urban ideological divide.