You’re comparing the wrong things. A specific release of Python or Ubuntu is only maintained for that long, but you can upgrade to the next version just fine, normally with little effort. (Sometimes it takes more effort, but that’s true of iOS workflows too.) If you have fifteen-year-old x86-64 hardware, you can probably run the latest versions of Ubuntu and Python on it. By contrast (using the figures from this thread), iPhones become less useful after about five years since you can’t get feature upgrades any more and so increasingly apps will stop working, and become unmaintained after about eight years.
What do you mean by “software support”? All I can think of that would be relevant is things like firmware/BIOS security patches. Honestly most people never need or get even that. But even if there’s an unpatched rootkit opportunity (which is unlikely to be practical to invoke), everything else in the stack can still be modern and patched, featurewise and securitywise. I’d say that’s normally good enough.
But even if we allow that, that’s a completely distinct topic, and my point stands; your Python/Ubuntu comparison was still clearly unreasonable.