That's a good point. They used to be the same across accounts, but then they had consistent capacity problems in us-east-1a so they introduced the shuffle which

That's a good point. They used to be the same across accounts, but then they had consistent capacity problems in us-east-1a so they introduced the shuffle which is determined on account creation. You can actually look in the "Resource Access Manager" to determine which allocation you've got, it maps the names you see in the rest of the console to e.g. use1-az1, use1-az2, use1-az3, so you can use that information to "colocate" things if you really need to.