@rogerponny
Ballet Shoes. The idea of the book is good, but it fails in its motivational function. Much of this has to do with the completely passive-amoebic behaviour of the girl protagonist. Personally, at the very least, I find it strange that Anna herself has done nothing for her dream; has not taken any decisive steps to somehow bring her dream closer. Yes, Anna says practically directly that she is a gifted ballerina and it is not her concern to find money for her own dance training. All means are good in the pursuit of dreams, and it's great when there are people close to you, ready to do a lot for the sake of your "desires". For any athlete or dancer who wants to make a name for herself to the world, achieving success and her goal is a personal challenge, not shifting the responsibility for its implementation to others.
Anna in BSFA is a particular type of character - like Posy - the single-minded ballet 'genius' as opposed to the talented all rounder (Pauline) or the merely competent because they've been taught well (Petrova, Francesco, Gussie).
In Streatfeild's world, normal rules don't apply to this character type - they must live for nothing but ballet, no matter if that makes them selfish or unreasonable (as in your example above, or Posy's reaction to Madame's illness).
You're right that this character-type's success depends on having tolerant, supportive family. Anna's brothers had been brought up to believe everything should be sacrificed for the sake of Art - their father had stolen from his family to run away and paint, but that was justified because he was a genius. It also depends on someone recognising the 'special spark' of talent, as Jardek had for Anna, and nurturing this.
In the 21st century, real world, amid millions of aspiring dancers, artists and so on, all egged on by social media, it's very doubtful that a 'special spark' would get you on without luck, contacts and hard work. But even BSFA, one of Steatfeild's last books, was written almost 50 years ago, and times were different then.