The average salary for a software developer in Montana is $88k/yr. The average salary for an HVAC technician in Montana is $58k/yr.

The average salary for a software developer in Oregon is $118k/yr. The average salary for an HVAC technician in Oregon is $74k/yr.

It's for sure less, but the gap is smaller than some might think. I think some markets (SF) distort the cost a bit.