The question should be, who is scarier Wano Samurai or Akainu?
Kaido is above of these things, he owns Wano Samurai, the Samurai are afraid of Kaido. Kaido > Samurai or Akainu.
Gorousei and CP0 will also answer this question without any hesitation.
People wouldn't be scared of a world government lapdog, when there is a guy who plans to conquer the entire world, plans to conquer places like Wano (which Akainu is afraid of, Kaido already conquered it), other new world territories, other non-government related territories, and government related territories.
Haoshoku Haki is also related to intimidation, and Kaido mastered CoC Haki, Akainu? We don't even know if he has it or not.