You're right about the dividing line being mucking with hardware (I'd also add 'requires access to large or expensive equipment'). But there are plenty of jobs

You're right about the dividing line being mucking with hardware (I'd also add 'requires access to large or expensive equipment'). But there are plenty of jobs that don't require face-to-face interaction but do require on-site work for one reason or another. Air traffic control, janitors, machinists, garbage collectors, geologists, bakers, etc.