Earlier quoted context omitted.
War in Ukraine does not validate that assessment: https://www.youtube.com/watch?v=XiGwWwcnT7M
War is the definition of "not cheap" because the stakes are so high (you die). Ukraine is building what it can with anything it can get and also in a constant race to adapt and develop superior designs. You're not seeing "cheaper": you're seeing a literal arms race.
"building what it can with anything it can get" is the definition of cheaper.
If it was easier or cheaper to create a multi-purpose robot to control vehicles and deliver bombs that's what we'd see Ukraine doing.