My company's policy is that retired laptops are destroyed. (I suppose properly wiping them or removing storage devices should be enough but for some reason it's not considered sufficient.)
There are indeed lots of second-hand former company laptops being sold, and some companies even specialize in refurbishing and selling them. I don't know what percentage ends up being recycled but it's definitely not 100 %. I'd assume the more security-oriented the organization gets, the more likely it might be to avoid recycling devices intact.
With that said, I haven't seen two-year-old high-end devices getting retired. But if there are only a few of them, and a large fleet is being renewed, I suppose it can make sense from a fleet management point of view to renew the few perfectly current ones as well.