Here’s an interesting article on why so many breeds of domesticated dogs have floppy ears. It covers territory I’ve covered here before.
It’s pretty simple, actually. Floppy ears are a neotenous characteristic (neoteny is when immature chaacteristics are preserved in adulthood). Dogs have been selectively bred from wild canines for reduced cortisol production and reduced cortisol production is associated with increased neoteny.
My breed, Samoyeds, have “prick ears”, i.e. they’re not floppy. However, they’re also white and white in the coat is also a neotenous characteristic.