Let say you were to develop an embedded device powered by Debian, Ubuntu, etc. The device is plug an play. There is no need for the customer to SSH into your device and make modifications. However, does the GPL license require me to give the customer full access to the Linux system in case s/he wanted to install security updates, add/remove packages etc.
Another example, let's say I buy a Roku box for my TV. Am I entitled to get Linux access to the Roku box so that I can maintain and run security updates?