Charities paying for the e-waste is not universal. Depends on your local waste management. But nonetheless, when a machine is disposed of /someone/ must pay for it one way or another. It’s cheaper to actually use it.

Your forgetting storage costs. The value of older computers often doesn't compare well with storage costs, particularly given the amount of time they sit there for. That's what does us in. We only have so much space, and dozens of computers can eat that quickly. It's similar with old monitors.

The pre-spychip AMDs have anywhere between 2 and 8 cores just before the last segment of 15h chips were made.

I wasn't sure where the cutoff was, in practice.

It’s a marketing problem. Consumers don’t know to demand pre-spychip machines because they are wholly clueless about it. A charity shop can manufacture demand just by being transparent in their sales info.

In practice, most can't. They don't have the reach to change people's views on the scale needed. They would also need to deal with people who didn't understand what they were buying. Older computers often need a bit of finessing to get the most out of. Sticking windoze 11 on them, and giving them out to OAPs or single mums is asking for very frustrated complaints.

That’s a good idea. Either way, it requires an intervention in the status quo. In my region, the public is blocked from getting access to rejected hardware, which goes straight to the (apparently secret) disposal site.

If you think it's viable, make a small business out of it. Tell the charity shops you will take the old laptops off their hands to repurpose them. Extra qudos to you, if you can mix and match to make, and donate a few "supercharged" computers that would be of use to their customers. Unfortunately I suspect the number of customers is too small however, and you would run into the same issues they do.