Volunteering allows students to get experience to get a job. Within such circumstances, volunteering may be viewed as a viable tradeoff. The volunteer learns practical skills and gets valuable training on the job, becoming more employable when a real, paid position becomes available. The volunteer is shown to be motivated and serious about long-term career goals in the GIS field. Therefore, free work is an acceptable tradeoff for real-world experience, at least for a while.
Volunteers can demonstrate industriousness.
By volunteering, GIS students can demonstrate how hard they work. They can show they can tolerate the tedious exercises of data collection, data entry and the interminability of digitizing. Students then can get the kind folks who employed them to write references that attest to these remarkable virtues. It seems a fair exchange, but only if it doesn't go on forever and the volunteers aren't exploited on the job. They shouldn't just photocopy and take coffee orders.