As some of you have mentioned the French Tennis Federation has a system as follows:
("simply" described to me by my sister in law, who is from France and played D1 tennis in the US)
- Everyone gets evaluated and ranked (rated)
- There is no age groups
When you enter a tournament you are placed against someone who has a similar ranking to you, if you win the match, you play someone who has a slightly higher ranking than you. The more you win, the better players you are exposed too.
Someone could be rated the same level, but play each other even though one is 7 years older than the other.
This system exposes players to many different gamestyles. You are constantly playing with someone who is as good as you or better if you work your way up. Unlike juniors now, you may have to play 2,3,4 matches before you play someone at the same level as you or someone who is better than you
Another aspect of French tennis in the juniors which I think is overlooked is about how the juniors travel to tournaments.
Many juniors belong to a club or academy and travel to the tournaments. When they go, its almost like a competition within the group. They compete to see who can make it the farthest or who can beat someone who is ranked much higher than them who might be in their 20's and so on. From what my Sister in law described to me it seemed like a very fun way to be brought up through tennis, very competitive but the kids love it and develop a passion. They aren't just playing because mommy and daddy bring them to a tournament each weekend, they play because they love the game