So, there have been some on going events in the fairy tales that I have noticed. And, they always have an impact on the tale and the end product.
Most people see mothers as loving and caring, therefore they could neve treat their biological children terribly like the characters in the fairy tales experience. So, most of the tales that have an evil mother figure are indeed stepmothers. Also, there is a lack of a father figure present in the tales because then the stepmother wouldn't be incharge as much as she is.
-Fairy Godmothers or help via magical creature
Magical help is often used in the tales however it is hard to completely say why. Personally, I believe that it gives that idea of a greater something that helps lead people into certain directions like a higher being.
-Miserable life before marrying Prince Charming
Of course the morals of these tales are that good, hard-working people end up with a better life in the end. Therefore if the heroine didn't have to suffer something unfortunate why should she end up so happy in the end. For example take Cinderella's stepsisters, they are vain cruel creatures who treat Cinderella like flith, however because she puts up with it she ends up happy in the end while her sisters end up with no eyes and defected feet.
-Damsel in distress
Most old fashion tales depict the heroine is some sort of trouble who needs her prince charming to saver her. However, recently in movies like Enchanted, which is a combination of many fairy tales, the main character Giselle saves her prince charming and ends up happy. Showing that women are now being seen as a strong gender, more so than they have in the past.
There are many more, however these seem to be the most imperative which help to lead to the ending the heroine always finds.