Seeded role Enterprise Contract Administrator automatically grants access to our Canada BU

Hi everyone,

We have noticed that when adding the following seeded role : Enterprise Contract Administrator (ORA_OKC_ENTERPRISE_CONTRACT_ADMINISTRATOR_JOB) to ANY user, this automatically gives access to our Canada BU, and this even without any data access added on the role. Also, adding data access to this role (adding any Business Unit, let's say US) does not give additional data when searching contract under the US BU. 

My questions are the following :

• Why does the seeded role AUTOMATICALLY and ALWAYS grant access to our Canada BU contracts?
• Why does adding other Business Units on the seeded role does not grant access to these BUs?