This phrasing unfairly conflates VM/hypervisor technology and containers. Containers being a pure software technology do require near superhuman ability to secure but VM/hypervisors can lean on chip-level separation.
People forget that in-chip memory protection didn't come about for security reasons, memory errors were a particularly dangerous and particularly common kind of bug and the hardware was extended to help with memory isolation. OS session ending memory errors are almost unheard of since operating systems have started fully utilizing the on-chip protection. Programmers didn't become "superhuman" at preventing these errors.
For similar reasons it's much easier for hardware-backed virtualization programmers to protect you from malicious business inside a VM than it is for OS or container programmers.
People forget that in-chip memory protection didn't come about for security reasons, memory errors were a particularly dangerous and particularly common kind of bug and the hardware was extended to help with memory isolation. OS session ending memory errors are almost unheard of since operating systems have started fully utilizing the on-chip protection. Programmers didn't become "superhuman" at preventing these errors.
For similar reasons it's much easier for hardware-backed virtualization programmers to protect you from malicious business inside a VM than it is for OS or container programmers.