Others have done a good job answering you, but I just want to add that there's a whole body of theory and scholarship that calls your mental model of this into serious doubt. It's called public choice theory and it essentially concludes that politicians, bureaucrats, and other officials are just as driven by selfish interests as anyone else, and that democratic systems typically do a very bad job at channeling that selfish energy toward the public good.
Forgive me for being sentimentalist a bit, but I think that nowadays we underestimate the weight that feelings of duty, loyalty, and trust had on rulers of times past. They were raised from the day they were born to be leaders, to care deeply about their family honor, to feel obliged to their subjects. Certainly, they were ultimately fallen men like the rest of us, and hereditary succession is not great at picking the best of each generation.
My point isn't that politicians are inherently better or more trustworthy than companies, but that you have more control over them. The amount of control as a community you can exert on a company beg enough to have a large influence in a community is minimal. The amount of control a community has over an elected official that oversees that community should be large.
There will be good companies and bad companies. There will be good politicians and bad politicians. One is easier to steer than the other.
Duty, loyalty and trust are good to have. What do you do if the large local company that has outsized influence on the community is lacking those? What do you do if the local elected officials are lacking those? Neither is easy to deal with, but I think one is a far more manageable problem.
Forgive me for being sentimentalist a bit, but I think that nowadays we underestimate the weight that feelings of duty, loyalty, and trust had on rulers of times past. They were raised from the day they were born to be leaders, to care deeply about their family honor, to feel obliged to their subjects. Certainly, they were ultimately fallen men like the rest of us, and hereditary succession is not great at picking the best of each generation.