It's not the standard, it's just something that started to pop up in some university courses. Anything before that we usually are just graded 1-6/A-F. But even 15 years ago when I attended University there were a few courses that required a 70%+ for passing and what I have heared this has become more common. It's basically to weed out people and reduce the number of students since university is usually free.

I think it definitely depends on how the course is assessed, what content it covers, and how much of that content the student needs to have absorbed to be considered to have met the requirement to pass. I just completed one in the UK where, to put it in simple terms, you had to get 10/10 to pass, and you got higher grades if you went above and beyond. But that's because each module had a set of criteria and you had to demonstrate proficiency in all of them at least once in the coursework, and you got extra credit if you demonstrated "very good" or "excellent" proficiency. (This grading system is unusual in this country, but it exists for very skills-focused courses, where demonstrating proficiency with doing something is more important than showing you know something.)

By that standard, a game with "only" 7/10 would have significant chunks missing in a way that would make it unplayable. A 10/10 game would be average: everything that's meant to be in there is there, but it's only done the bare minimum to make a functional game. Every part of the game that could be described as "very good" or "excellent" would earn it ratings above 10.

Not that I'm saying games should be graded this way. It'd be ridiculous and confusing. But it just demonstrates that what constitutes a "failing" grade definitely varies not only between countries, but between different courses. Which means I actually agree that basing game reviews on the grading system of the US educational system is flawed: it makes too many assumptions about what constitutes "passing" or "failing".