This is why I hate grouping by levels. Don't get me started. We have now been in several gyms and my favorite is there is a group 1,2,3,4 situation. The groups are formed considering level, ability, work ethic and goals. The groups have several levels in them and they overlap. Ex gr 1 has 8,9,10 and group 2 has 8,9 and group three has 7,8 etc down the line. Group 1 and two have the same hours and same coaches and it goes down from there with excellent yet assistant coaches verses the he'd coaches coaching the first two groups.
All the kids get what they need. Getting hung up on everyone getting the same will just lead to frustration because I have been at this a long time now and the reality is that some kids get more. It just is what it is. Now, that doesn't necessarily mean the others are getting worse.
Let's take the OPs scenario of group a and b at the same compulsory levels with the higher scorers going to the a group. This actually makes a lot of sense to me. The kids who are already scoring very well at meets are working on perfecting their routines and nailing pressure sets. They may not need as many numbers as the lower scoring girls on this stuff and that leaves more room for uptraining.
The lower scoring group needs more time perfecting the skills for this level and a higher number of routines to perfect all those details they need to be working on if they aren't scoring high.
Can this all be done with the kids all mixed up? Yes, with individualized assignments and independent work, which is how it is done in combined level groups up in optionals. But, if you have enough kids for two groups then it seems it would be a lot more efficient and work better for all the kids involved if they can split them and easily give each group what they need.
This is hard for parents on both sides. It is easy for us all to feel bad and sympathize with the kid in the lower group that wants more but I am just going to say (and will probably get bitten at for it as that is usually how it works) that as a parent of a kid at the other end of the spectrum it is frustrating there as well. When your kid is capable of more and wants more and the resources are going to the masses because no one wants to upset anyone by giving more to the kids that need it, it is very frustrating too. There are always two sides to every situation.
The coaches are doing their best to manage the situation in their gym the best they can. I have never met a coach who wasn't working their asses off to give every kid what they need and help every kid reach their potential. Sometimes the situation is tricky to manage and sometimes they make mistakes. But, in general, they aren't trying to help some succeed and not others, it's just that success looks different for each and every one of them.
The cold hard truth is that not every kid is capable of the same. This sport is brutal on the ego of parents. Just when you think you have it all figured out and are feeling confident, it will beat you down and humble you like nothing else. Some kids have so much talent and things come so easy and some of those kids make it and a lot of them don't, some kids have good talent and an excellent work ethic and find success and some have a lower level of talent or their body isn't perfect for this or it is but injuries take it all away. You can't predict and that is why everyone always reminds us that it is about the journey and not to get caught up in the outcomes. Your child is building life skills that it is difficult to get elsewhere and that has to be what it is about even if that means coming in last or going to the olympics.
You must trust the head coach and the philosophy of the gym. You will travel through lower level coaches and they will come and go, but you must buy into the program. If you don't know what the philosophy is or what the program means then ask the head coach or owner of the gym, whichever is accessible to answer your questions. Once you understand you either need to buy in and trust, while maintaining communication of course. Or, you must leave and find a program you can believe in.
We just had to leave a program, not because there was anything wrong with what they were doing, but my dd and the head coach could simply not get on the same page and the philosophy of their program wasn't something she could live with or succeed in. So, we found a program that does work for her. Simple as that.
Sorry... I did it again.