Does this help in the hypothetical case OP is mentioning? Or does the government coverage kick in only after the person has been made to spend every last dollar that they have on the mandatory treatment and are now left penniless?
This is not necessarily true of other diseases. But TB's legal complications plus its serious nature make it essential to handle it this way. It's cheaper for the local health department, too: think of what has to go into evaluating and testing all the people who ended up with a preventable exposure. I remember a case in which we tested over 5500 people because it was a nurse and they weren't detected for six months.
Outside of an HMO, what does this mean? You cannot “see” or be treated by most insurers in the United States. You “see” a licensed provider, then some time later find out what, if any, of the charges billed by those provider(s) are covered by your insurance plan.