How can we know?

This is part of the challenge with these regulations - by definition we're defining a framework based on existential knowledge.

What about batteries that can also be panes of glass that act as the display? What about ultra low-power devices that are powered kinetically by typical human movement or magnetic perturbations?

None of these currently exist in a commercially viable form, but if we regulate based on our current view of technology do we run the risk of making these innovations more challenging to bring to market? That's the challenging balance that needs to be considered.

The regulation gives manufacturers quite a lot of leeway on how easy it is to replace the battery. You could make the display a battery, just make sure users can replace the display with pull tabs, a set of precision screwdrivers and whatever other commercially available tools you want. And from just skimming the regulation, I don't see how devices would be forced to have a battery. It talks about devices with batteries, and batteries in mobile phones, but if your device doesn't have a battery then this regulation simply doesn't apply.

History is littered with examples of policy creating unintended consequences causing more harm than good. Or at least negating the early good it created over time. It’s usually fine at the start until cracks start to show and policies are often a one way street, that only get reformed many years after the problems become apparent, if at all.

It's also littered with examples of a lack of policy causing untold harms. A light-hearted one would be the time libertarians found out that policy helps keep the bears away[0].

The answer isn't to abandon policy, it's to design it to be flexible and to respond quickly when problems are discovered.

[0] https://www.vox.com/policy-and-politics/21534416/free-state-...