Why is Contacts.app's "General" tab different on two Macs with the same software? I have two macs, a 2010 MBP and a 2013 MBA. They run identical software: both use macOS 10.12.6, and Contacts.app 10.0, build 1756.20.

The "General" pane of Contacts.app's Preferences displays differently on the two machines. The MBP shows this:



while the MBA shows this:



Why are the panes different?
One Mac only has one account set up, so there is no "Default Account" option. The other Mac has multiple accounts set up, or one account and local data, thus it gives you the option of choosing a default account. What else is listed in the "Default Account" menu?