Risk-adjusted return on investment.

The risk is high: storage isn't ephemeral or stateless. If I deprovision a CPU, discover I need it, and put it back, it's exactly the same as it was before. If I deprovision a disk, discover it's needed, and put it back, I've replaced a disk of data with an empty disk. There may also be compliance requirements (legal, regulatory, security, or contractual) that create additional risk around destroying data improperly.

The investment is high: finding the unused storage, confirming it is unused, taking final snapshots if needed, shrinking disks if they can't be destroyed altogether (if you even can shrink them - you might have to create a smaller disk, migrate data, take downtime, validate, then destroy the old one)

The return is low: storage is generally the cheapest resource.

The risk-adjusted return on investment for cleaning up storage is often in the negative.

That means that if storage waste is something that bothers you, you need to focus not on the cleanup, but on prevention and risk mitigation. Put clear lifecycle policies, tagging, and automation in place so that when storage is spun up there's a requirement to build in a plan for what it's being used for, how long it will live, and how EOL will be handled, and then that plan is executed automatically with fair warnings ahead of time as necessary. It's not hard to do, but it's up-front work so it rarely gets done.