My guess is people who work on crafts also will need to pay for the electricity, and also the rent, you know for the roof above their heads, and water, for the bathroom and such.

There are EXTRA expenses in the creation on non-digital art.

If you want to get nitpicky, yes, working digitally has the cost of the electricity and the computer, but you would be spending that money anyways if you listen to music while you painted a commission with oils.

On the other hand, you won't be buying oils unless you produce stuff with them.