That's not true, in a democracy you tend to have methods of appeal that actually work, and their threat keeps the wheels of bureaucracy greased.
This is because, in principle, everything comes down to the fundamental threat that the people can remove the current government, and the government does have full control over the unelected civil servants. If they keep ignoring appeals, they'll eventually get dethroned.
There's a nice symmetry between this and the fact that the law is ultimately guaranteed by the governments monopoly on violence. They can dethrone you too if you don't comply.
When a democracy works, there can be a very effective balance between the people's leverage towards the government and the governments leverage towards the people.
In an authoritarian regime the same forces are present but they are not balanced in the same way. The people can still rise up and dethrone the ruler through violence, but that is so much harder, and it is mostly offset by the governments greater power of violence. So they can get away with so much more.
The US elected government has no control over the unelected civil servants as congress over the past 150 years did everything they could to prevent the spoils system.
Elected officials have significant influence they can bring to bear on specific decisions, general operations, and in many cases personnel decisions. That’s true at the level of individual house members and can be more true for other offices.
The rule of law and checks and balances also means these elected officeholders don’t have arbitrary control, which has a lot of upsides (and produced a professional and effective federal workforce) as well as some limits.
I swear we have a problem where we quantize to caricatures rather than recognizing tuned balance, and control theorists would probably anticipate this means things will start to swing a bit wildly.
Executive power over the civil service is an ant driving an elephant. You can say it's a good thing and it's intentional, but the fact of the matter is that the executive appoint a fraction of a percent of the positions and those positions have nominal personnel powers that they can't really use without fear of getting sued.
I think this is completely wrong. For a democracy to form, substantially everyone must have bought in. That’s the upstream, not the threat of removal. Authoritarian “regimes” are constantly under threat of removal.
This is one thing many forget, mostly due to drinking our own koolaid about the inherent superiority of liberal democracy. Authoritarian regimes almost by definition have high public support, because they couldn't function at all if even a relatively small proportion of society went against them. The people who want to overthrow them are either out of the country or insignificant. Dictatorship is impossible without populism.
This doesn't make any sense to me. There are and have been numerous authoritarian regimes that lack "high public support", now and in the past. The entire idea for most authoritarian regimes is to slowly minimize the power of those who oppose them. And then, they spend a huge amount of resources looking for dissent (SD/Gestapo, Stasi, etc.) and trying to control the societal narrative.
Any government that lacks public support collapses.
Democratic governments can operate without a plurality of support for the current government, because the population generally supports and is invested in the system of government. When democratic governments fail, there is usually very little danger of violence or economic and societal instability, because there is trust in those systems. Corruption and malfeasance harms trust in the systems of governance which democracies depend upon.
Authoritarian governments depend on confidence in the government to continue functioning. The system of government isn't necessarily trusted, the workers of government aren't necessarily trusted, but the leaders are in charge and doing things. Media manipulation and effective propaganda is certainly an important tool for these governments, but pointing out that it exists doesn't mean that it doesn't work! Propaganda totally does work, by almost all measures. Russia, China, Cuba, Iran all have high domestic support for the government.
Authoritarian governments also tend to be very stable - people know what to expect. Democracies change periodically. The stability and familiarity are key to the trust that authoritarian governments maintain. The protests in Iran prior to the current conflict are a good example of what happens when a government fails to maintain the trust of the people - the arrival of war saved the current regime from falling apart at the seams when Khomeini died of cancer in a few months and a squabble for the leadership broke out amid a collapsing economy.
I think that you're underestimating the power of authoritarianism. For Iran, I don't think the government was in any danger prior to the war. It was capable of exerting control through the state apparatus quite easily. And look at North Korea, you think that the people under that government are supportive? That's nonsense on stilts.
Also, that collapse you refer to can take an awful long time under authoritarian control.