But it doesn't work when you need corp IT for corp IT integration
Since you don't have to comply with tax codes for internal budgets you could even allow developers to choose (within reason) which deprecation period to use for each item.
Perhaps some generous budget limit, with a clear message that it's not intended to be fully consumed, and a clear rule that a certain percentage of whatever will be left at the end of the year is donated to some universally accepted good cause? Children and cute animals, please not religion. "You can get the book, no problem, but keep in mind that being the book means $5 less ponies!" (just don't make it manatees, you'd risk me working on a chromebook)
What expense policy survives a decade or two completely unreviewed and unexamined? The rest of the bullshit you spewed isn't worth reading after that bizarre hypothetical.
This is the problem. Management inserting themselves into any and every decision. People think management are there to help but they cause more problems than they solve. They are truly incompetent at best and a better idea is to fire a few managers and use their salaries as the discretionary budget. Win-win.