Trebling is one of the hardest tropes to take from a tale to a novel. (Short stories, I shudder to think of.) The laconic fairy tale allows things that look absurd when drawn out.
Not just riding on a fox's tail. That's the sort of absurdity that happens. It's things like a prince born a pig managing to find three brides in rapid succession after he killed the first two -- even after they tried to stab him as soon as they were wed. Arranged marriages or not, that makes you wonder why all the potential brides did not run away to become scullery maids. Especially if they had starry-eyed dreams of three balls, and demanded three splendid gowns to marry him.
It's up there with the habit of dropping characters like hot potatoes as soon as they serve their purposes. A wicked stepmother curses her children into swan form and we never hear about the kingdom again. What happens when all the royal heirs are disenchanted in a foreign land and never return?