Uhm.
"cheaper than before" usually yes.
But we are talking about different production methods, maybe hydroponics could never be cheaper than growing stuff in dirt because the production method can be optimized only so much.
An "advanced" (different) production methods is not inherently cheaper than a "traditional" method.
Hydroponics usually isn't competing on cost, it's competing on other axes, such as having a greater amount of control. Just the same as greenhouses vs growing in the open. Farming is mostly about dealing with or preventing everything that could go wrong.