From a supplier standpoint 01005-size chip resistors require very advanced thick film deposition equipment with extremely tight process control as well as more advanced thick film materials. Beyond that, they require advanced laser trimming systems for calibration and very precise breaking equipment and processes to treat them.
But maybe the most absurd of all the issues in manufacturing this size of resistor is that the packaging constitutes nearly 70 percent of the total component cost. When the part actually gets to the customer for building the end product, estimates currently show the successful placement rate for the 01005 chip resistor is around 90 percent.
This means 10 percent of the resistors manufacturers buy don’t even make it to the board because they are lost in the placement operation.
Clearly, unless the product you are building is forced to use resistors of this size, it makes much more sense to stick with at least 0402 sizes or to switch to a chip resistor array to reduce component count and increase density while also lowering total acquisition cost per resistor.