Containers are not isolated VMs due to sharing a common kernel, which is the main idea behind their lightweight nature. Sharing a kernel with unknown containers can be uncomfortable and raises concerns about security, much like double dipping at a party. The level of trust in sharing a kernel varies among individuals, ranging from those who wouldn't share with strangers to others who are more tolerant or even adventurous. Understanding the implications of running multiple containers on the same kernel is crucial for effective use of containers in production environments.