Shanks is the only yonko who actually kills. Big mom and kaido make people who attack them their slaves. White beard makes them family. But not shanks. You submit or you fucking die. That’s why shanks was never called the strongest and doesn’t have the reputation the other yonko gave for durability but is feared by them. Even if they could beat shanks, his officers are stronger than their officers. And all yonko, even kaido, have been shown to love their officers. So I think they don’t want to fight him cuz his officers will slaughter all their offfiers. That’s why the marines are scared too. I don’t think the red hair pirates fuck around. You fuck with them and you die. I think kidd supports my theory. I know this is technically head cannon and can’t be proved but it’s my theory.