If they have to buy a laptop anyway, spreading the cost over the life of the equipment turns a capital expense on the balance sheet into an operating expense on the P/L statement, and can have some pretty nice tax benefits (jurisdiction dependent of course).

Often plant and equipment is financed this way - photocopier for example are seldom purchased outright, and come bundled with service, support and consumables.

Many major PC manufacturers already offer leasing, which could effectively be thought of as a subscription: https://www.dell.com/en-us/work/learn/dell-business-lease

I wonder what the depreciation tax differences would be? For us we buy hardware in the 'on' years (our business runs in 2 year cycles)

I'd imagine so, given that's what hosting services like AWS are (along with the related software).

Doubt it - most businesses barely want to shell 5-10$/mo for a single user license of software.

It does. We lease all our laptops.