> why is it ok for a group of people calling themselves the government to force everyone to buy their services?
If you are in a country that allows you to vote, then you are the government. In most countries, you are free to leave. You can go to a country that doesn't collect taxes. Somalia, for example.
You can vote but if you only have the choice between candidates of the system that lie to be elected and say they are different, it is hard to change the way things are.