Let's take a closer look at how you would work out a low board in practice.
Here the best low hand is hand A. His low hand is 7-6-5-4-2 for a Seven low. Hand B is an Eight low with 8-4-3-2-A. It matters not that Hand B has an Ace and lots of other very low cards. Your low hand is defined by the highest card, not the lowest.
It is very common for two players to each have the same highest card in their low hand.
Both of these hands are Seven low. In such cases it is the next lowest card which splits the tie. Thus the Seven-Five low of Hand B (7-5-4-3-2) beats the Seven-Six low of Hand A (7-6-3-2-A).