[nynx]

For better or worse, computation is not unifiable. Each computation generally needs a certain amount of storage space, a gpu that can run N trillion floating point operations per second and K billion tris per frame, etc. You cannot pick a single number, in a reasonable way, to represent all that.

[merwanedr]

On Ethereum, executing a function on a smart contract means you're doing computation and maybe writing data, which involves both CPU and disk. The amount you pay for running this operation is denominated in gas, and is determined by things like iterations, memory used, data written, etc. The end user doesn't get all of this separately, but instead gets a unified computation price. Maybe it sounds unclear at the current scale of Ethereum (which can only perform basic operations), but at a larger scale, we could unify the cost of remote computing in a single metric.