AT&T has an A+ rating with 94% of reviews being negative/complaints. They get a grade of 6%.
United National Ministry has an F rating with 100% positive. They are not a “member”.
You can find many other examples of this sort of intentional misleading. BBB used to be a trusted source for consumer protection. They’ve sold out. Read the reviews by customers.
The letter grade is only an indicator of how much BBB is paid by the business. The letter grade is not usable by consumers.