Well, why wouldn't it give an advantage to do four subjects at a higher level than three at that level and one at a lower level? It makes sense. It's not much of an advantage since doing four A2's is uncommon. They cannot score AS the same, now THAT would be unfair.
It is similar to how Leaving Cert subjects are scored. All subjects can be taken at two levels. An A1 at higher level is 100 points, but only 60 at Ordinary level and they go down bigtime from there. Because the Leaving Cert requires you to be very well rounded, a huge majority do at least one subject at ordinary level. And plenty do two, which means they automatically have no hope of anywhere near top points. And even with one, there's huge pressure to excel at all 6 subjects because you have no margin for error. Therefore people who are great at all 7 and do them all at higher level have a distinct advantage. But not an unfair one.
Tell your friend to pick up an A2 externally, it will greatly help her if she wants a course with high points here. It's also worth noting that the vast majority of courses are under 500 and do not need 4 A2's. It is a small minority that do but they are the ones in demand by their very nature. But it reflects poorly on the entire system when it just isn't the case for 90% of courses.