[keithg]

In addition to being physically hard work, you need to get out and go to the job site. That incurs overhead in the form of fewer billable hours per day. So if you're 30 minutes to/from a 1 hour job, your rate is effectively cut by 1/3.

I'll add that it's pretty comfy sitting on a soft chair in an air conditioned or heated office to work.

[XorNot]

I ran straight into this when I was doing chemistry lab demonstrating last year. The job pays pretty well for what's asked of you...but since I wasn't actually at uni at the time, it meant I had about 1.5 hours of commute for a 2 hour lab period where I got paid. Which made the rate far more ordinary.

Still doing the same thing this coming semester, but since I'll be an undergrad and it'll run straight to classes, the value proposition is much better.