Suppose someone exclusively receives money via bitcoin and their name is in no way linked to the bitcoin address. Yes, they are probably anonymously receiving money. But, if they are purchasing any actual physical goods, the IRS knows they are receiving money somehow. They better be reporting them as the IRS likes to look into people who have spending that is out of line compared to their income.
Also, from the FSF announcement: "Because of the way the system works, contributions to this address will not be fully anonymous."
Also, from the FSF announcement: "Because of the way the system works, contributions to this address will not be fully anonymous."