Didn't chroot() become secure / usable only late in the era of smartphones, way past creation of Android? Containers are a pretty new development, after all.
Neither linux containers nor linux chroot provide meaningful security. They’re useful for other things, but the kernel itself isn’t particularly well hardened against local privilege escalation attacks.
OpenBSD is one of the best on that front, but it is a defense-in-depth mechanism, not something designed to run known-malicious code.
OpenBSD is one of the best on that front, but it is a defense-in-depth mechanism, not something designed to run known-malicious code.