Why would parts and service be more difficult for 2nd hand owners vs original buyers? The model should be the same. Schedule in the app, take it to a service ce

Why would parts and service be more difficult for 2nd hand owners vs original buyers? The model should be the same. Schedule in the app, take it to a service center. If anything, I'd wonder about warranty vs off-warranty. But don't they have even MORE of an incentive to service off-warranty vehicles which represent a revenue stream vs a cost?