I agree with the sentiment but to a certain degree you can vote with your currency. Also, in many places you can certainly vote for elected officials who are interested in using government tools to prevent and breakup monopolies.

Right, and people do vote with their wallets. They vote for the iPhone. We don't have iPhones because they exist; they exist because we keep buying them. This isn't a chicken and egg situation. Apple offered people a deliciously simplified computer in their pocket and people wanted that more than they wanted control. Their app store model hasn't meaningfully changed in almost two decades (except for whatever malicious compliance they're currently deploying in the EU). so to really examine the scope of the problem we need to acknowledge that almost everyone had a hand in creating it. I researched and ordered a new router that runs on open-source software today, and started setting up a Linux server. And now I'm in bed, scrolling HN on my iPhone.

Another important difference is that at least in theory the end goal of a government is the well being of its citizens, while for private companies it is profit.

Another importance difference is that you can pick the companies you use, even if you're a minority in your electoral district. (Except monopolies, of course).