That Java runs on the SIM, not on the AP. The DVD equivalent would be the Java running on the DVD itself, but a DVD is an inert plastic and aluminium sandwich. And even if it looks portable, it’s not. In practice there’s just enough quirks that code written for one Java Card won’t reliably install and run on all others. Actually portable Java Card that would work like DVD codecs would need to work didn’t come until eSIMs, which is decades later.