This is a shortcut for taxing unrealized gains. They start with NW >100 million and start decreasing the concept of Ultra-Rich until everyone non-broke eventually pays it. In Spain it happened with the Work Tax which from >60k EUR (68k USD) goes to 45% as if earning 3k EUR (3.4k USD) per month made you rich.
American tax numbers are only a little lower, but do not include health care. An American employer is likely paying around $8K for a single person or $20K for somebody with a family. That's a real and very heavy tax that Americans pay.