Because Doffy spent years mastering his devil fruit as his main power meanwhile Big Mom was just a born monster and Kaido focused on his haki…
Big Mom and Kaido didn’t show awakening because they don’t have it.
Doflamingo turned buildings into strings, and then got promptly smacked into the dirt a few minutes later.
Kaido possesses:
-Massive AOE attacks in Dragon form
-A variety of different forms (similar to Chopper using the Rumble Balls) when in Hyrbid form, including his drunken mode
-Incredible durability (the biggest indication of Zoan awakening based on the beasts from Impel Down)
-The ability to turn himself into a giant dragon made of flames/magma so hot it melted Onigashima's horns, when the entire island has been taking a beating the entire time without being destroyed. Onigashima survived so many attack, and Kaido's ultimate move melted part of it straight off, and burned Luffy to the point of severe pain
-If I'm supposed to believe Doflamingo making some Silk Stabby Things is Awakening, then Kaido turning himself into a giant death Dragon capable of melting incredibly hard material is Awakening
And Big Mom literally HEALED HER OWN BROKEN BONES WITH SOUL POWER.
Yonkou are the strongest Pirates the seas possess. It makes no sense to have the strongest pirates not possess the strongest abilities. Why in the hell would Doflamingo, Kaido's underling, have Awakening, when Kaido doesn't? That's like Nero having stronger Rokushiki than Lucci, get out of here.
You think Zoro has Adv CoC, and Mihawk doesn't? Top tier are top tier. Yonkou, Admirals, Dragon, Mihawk, are top tier for a reason. They're the best of the best.