It's belief based on a small dataset that doesn't represent all democratic governments that exist. If anything, your experience is probably based on significant outliers.
Slavery, Prohibition, Women being unable to vote, Gays being unable to marry; the list of inequities imposed on others due to democracy, and faith in the State to "do the right thing" is long. The aforementioned aren't small data sets, nor are they outliers. That's not even mentioning how many murders the State has contributed to (see: Germany and Russia for significant contributions, in the millions of murders) under the guise of "protecting it's people". (see: USA's actions in Iraq, Afghanistan, Syria, etc.)
Slavery, murder, theft, are inequalities that humans do to each other which the state exists to prevent. This argument is a poor one. You can't simply pick and choose the negatives without balancing it against the positives.