The harsh reality is that most scientists are not sieving through every statistics book they can get their hands on in order to find out all the reasons they might be wrong. The "individual motivation" to become statistics experts is only present in a few fields, and in the others it is ousted into applied courses taught by other departments.

Statistics is directly necessary in ML, so it's a "profit center" and emphasized. In many sciences it's treated like a cost center (something that you need, like IT, but that lies outside of your central expertise.)