The test is given to people who doctors think are showing symptoms of brain problems. That is why your parents have not taken it routinely. it is not designed to be tough. It is just to show if something is wrong. It is an easy test. The fact that the stable genius thought it was tough is revealing. The test was quickly put out on line showing what Trump thought was so hard. Yeah, picking a camel, an elephant and a rhino out is quite tough. That was impressive for him to accomplish that. Counting back from 100 by 7s, real math depth in that one.
Trump was sure that Biden could not handle such a complicated test. He saw it as a real accomplishment.