Whatever you call it, a fine or a tax (which by nature both are punitive, and both are used to compel you to do or not do something), are forced coercion under threat of government penalty/punishment.
In effect they are using their power to compel you to buy or not buy something. If you don’t they punish you. How is that not forcing you to buy something. Otherwise something bad will happen to you by the government. If that isn’t de facto forcing you to do something (else bad stuff will occur to you - fines, jail time) I don’t know what is.
Now we know why he had to hire many more IRS agents and an {”national security” gang to oversee this bill. It has nothing to do with health and everything to do with control