Source: Surface RT today is still getting security updates. And will continue to get them until 2023. However, it doesn’t matter much in practice. And that’s a quad-core Cortex-A9 clocked 400MHz higher with twice the RAM.
It's quite trivial to install LineageOS, for instance, on an old Android phone. Apple completely blocks this route. If your iDevice is no longer supported, it becomes a shiny, expensive paperweight.
My issue is that I see tablets as computers, and yet I can't even run an updated browser on a fairly decent computer released only nine years ago.
Apple also makes it very hard for more savvy users to install something else on their hardware, so once they stop supporting it one's forced to recycle it.
Perhaps I shouldn't have mentioned the iPad, but a thousand-dollar iMac from 2010 no longer being useful is quite sad, IMHO. My 2005 NEC laptop is still going.
Try to update the OS on a 9-year-old Android tablet, see how it goes.
1. My brother has a old iPad (3rd generation). Somehow its battery is still good enough and the screen is in great shape, but the OS hasn't been updated in years. IIRC, Chrome is stuck on version 60 something. I could jailbreak it, but apparently I'd need a Mac to do that.
2. A friend of mine sold me an iMac 2010 for 50 bucks last year, peripherals and all. The hardware was in excellent shape. When November came, Apple stopped maintaining the latest version of the OS I could possibly get. Due to that iMac's finicky graphics card, installing a user-friendly Linux distro such as Ubuntu wasn't trivial. I ended up donating the computer to a repair centre.
So here's a company with no interest in its hardware being of any use a decade after it's released.
Planned obsolescence is bad enough when done to phones, it should never apply to full-on computers.