> It is ideological. Many point to private courier services as an 'obvious' point of comparison.

On a couple different levels:

1. Some people (like libertarians) have an ideological opposition to government-provided services, and believe all or nearly all services provided by the government should be abolished and replaced with the "free market."

2. An ideological belief that private business is "efficient" and government is "bloated and wasteful" by definition.

3. An lazy belief that "the government should be run like a business," therefore the tools you use to evaluate a business (like profitability), should be used to evaluate government.

4. etc.

I think those are distinct beliefs, but they kind of feed into each other and support each other. Like if you believe government services are wasteful and business efficient, it would follow you would improve things by abolishing the government services.

There are good libertarian arguments for a government run post office -- particularly in how it support free speech, the right to petition, free and fair elections, how it uniquely protects 4th amendment rights, etc.