I think we might have a different definition of Virtualized and containers. I use IBM’s and Comptias definitions.

IBM’s definition is

Virtualization is a technology that enables the creation of virtual environments from a single physical machine, allowing for more efficient use of resources by distributing them across computing environments.

The IBM page themselves acknowledges that containers are virtualization on their Containers vs Virtual Machines page. Just because it shares it’s kernel space does not mean it’s not virtualization. I call virtualization as an abstraction layer between the hardware and the system being run.

Comptia’s definition of containers would be valid as well. Which states that containers are a virtualization layer that operates at the OS level and isolates the OS from the file system. Whereas virtual machines are an abstraction layer between the hardware and the OS.

I grew this terminology from my comptia networking+ book from 12 years ago though, which classifies Virtualization as “a process that adds a layer of abstraction between hardware and the system” which is a dated term since OS level virtualization such as Containers wasn’t really a thing then.