As far as I’ve read, historically speaking, most assassinations are crimes of passion. When Japan’s government was “government by assassination” in the early 1900s, most of the assassins were not hired guns but instead true believers. Ultra nationalists who were proud to “die for the cause”.
When evaluating a mystery you need to be careful not to sell yourself on the one that is more titillating, all things being equal. The story that involves unbelievable sadness and anger is usually more likely than the one the involves deception and intrigue.
I think it's just that political assassinations are better documented. Money flow control-related stuff usually goes unnoticed, and frequently there are all parts involved that would prefer it to go unnoticed.
When evaluating a mystery you need to be careful not to sell yourself on the one that is more titillating, all things being equal. The story that involves unbelievable sadness and anger is usually more likely than the one the involves deception and intrigue.