Once government has had a monopoly of a creative activity such, for instance, as the delivery of the mails, most individuals will believe that the mails could not be efficiently delivered by men acting freely.
Is that really why people push for some services to be government provided? I thought it was because some services are too easy to abuse, such as the ancient Roman fire services that would buy burning houses at a steep discount. Or modern US healthcare, that does all it can to hide prices from patients. Or ISPs and phone companies, selling browsing and location data.
And are men not acting freely if their activities are tax-funded? If market forces compel us to purchase a product or take a job (e.g. in a company town, for scrip), this is freedom, but if we democratically agree to communally fund a service, that's serfdom?