This is my personal experience with the grading systems and how I find (personal opinion) assigning grades as a very hard problem.

I did my undergrad outside the US but in a university that follows American system. My department culture was that you don't expect curves and grades are based on what you get. So if we are all getting F then that is F for all people. No one passes a course just for the sake of passing. While these extreme cases never happened (at least when I was there). if it happens then this tells about quality of the course itself not only students effort and performance.

I took a general relativity class during my undergrad. I like this field and topic. And while I am currently doing particle physics but I always liked GR. I was doing well regarding the topics but never got good grades. I struggled with its exams in particular with this particular professor. I got C although I managed not only to have a good grasp of the subject but went so far as to work on specific problem and expanded it into a paper, participated in a conference and got it published later into a peer-reviewed Journal.

While when I moved for a graduate school is the US. Things is very different. Many of the undergraduate I teach were always expecting high grades anyway. curving is very much the norm and the negotiations is about how much to curve. The normal distribution of the grades is a religious belief to some people in the universities administration. And I understand it is hard to assist professors teaching and some use this as an evaluation metric but it I feel like it doesn't addressa core thing. Some people will pass even with high grades and they did not get the core of the subject. This is not about they deserve more than me or not. There is a fundamental question of are we grading on effort to learn or actually what people learned. The grading criteria will differ much based on our answer to this.

In your profession effort to learn new thing is the most important thing. But with the degrees that assumes that you are ready if you have it is that the expectation or your effort and ability to learn. But how can wr measure that specially on scale.

During my graduate courses I took a QFT class taught by condensed matter physicist and was focused on his area of research. I wasn't interested and it was very tough. I don't feel I understood most of the things and I struggled to the point I did not submit the final exam (take home). And to my surprise I got an A because I was the highest grade in my class (we were few anyway). I learned a lot of QFT later on my own but I am giving this example on two completely different personal experiences that hopefully deliver the idea.

It is hard to design a grading system on a scale that will try to measure different things. and the universities marketing for degrees is doing much harm ( for financial reasons). And also graduate schools and companies don't usually want or sometimes doesn't have resources to look into details about applicants institutions even if they have information about what their grading works. Hell I don't even think it is possible to have one unified system per university (Is it even good thing to do?).