Most ambassadorship only means you get a deeper discount than others. Kids do not get paid if others use their codes. Many families (hundreds to thousands of followers, not professional influencers) do it to get a few discounted Leos and boost kids confidence.
Of course large scale influencers are different stories.
Parents have full control of the accounts. You can simply set it as private! And only approve followers who are friends, families, classmates and fellow gymnasts. Again, gymnasts don’t get paid when people purchase with their discount codes (really, 10 or 20% off is nothing, who would bother to use it, just wait for a sale), so there is really no need to “sell” the product.
At the end of the day, how these accounts are run and how content is created is really based on “wants”. The ambassadorship is just a stepping stone. Parents who make the account that way is because they “want” it - making it big so it can be profit making from future business opportunities.