Well it should not be too surprising: Most MSPs are SMBs, most SMBs have no grasp of finances. It's pretty general. As an MSP, if we talk to our customers, they often have no idea about finances.
Just look at things we run into all the time in the field: blatant disregard for the sunk cost fallacy, disbelieving in the concept of value and looking at price as a proxy for value (in randomly either direction), no idea of the time value of money, unable to look at risk as a cost and use this to evaluate needs, pushing CFO duties onto other departments that lack training and insight into the books, buying products without regard for suitability, paying for advice that is ignored, buying without planning...
SMBs don't just lack the knowledge of the complex stuff, they often lack the knowledge that we expect children to have. The struggles are often with the most basic concepts, not advanced ones. Ones that don't require training, just general knowledge.