Ever tried to security-update a vendor-provided container which you should never touch because of the vendor's support and warranty conditions? And even if allowed to touch it, the mess that it usually is: app running as root in the container, stuff chmodded a+rwx -R, weird base distro, build script is just a wget, cp -R or "this binary magically appears from somewhere". With a helping of " only works if the directory structure and environment look like the devs machine".
Containers are the ultimate expression of "it compiles, let's ship it" laziness