Statistically, it happens more than you might imagine. That's especially true of General tags, though it also occasionally happens with LE and OIL tags. Sometimes it's just personal issues or scheduling and sometimes it's bad weather or fires or access. I also suspect there are even some anti's involved who want to save animals. In any case it was about 5% to 10% before unit hunting, but it's now closer to 10% to 20%
Random Examples: 2018 Gen Rifle Buck Deer:
Cache- 2876 tags-2555 hunters afield = 11.2%
Kamas- 1253 tags-1002 hunters afield = 20.0%
North Slope- 1404 tags-1204 hunters afield = 14.2%
South Slope-Bonanza/Vernal-520 tags-458 hunters afield = 11.9%
LaSal Mtns- 686 tags-567 hunters afield = 17.3%
Nebo- 1742 tags-1419 hunters afield =18.5%
Oquirrh/Stansbury- 1231 tags-1115 hunters afield = 9.4%
SW Desert- 391 tags-338 hunters afield =13.6%
Beaver- 1427 tags-1280 hunters afield = 10.3%
Monroe- 532 tags-449 hunters afield = 15.6%
Thousand Lake- 109 permits-88 hunters afield = 19.3%
The same thing happens with Antlerless deer, Bull elk, and Antlerless elk. Hunting just isn't as high on the priority list as it used to be, I guess.
Edited- FWIW, the DWR calculates success rates based on the hunters afield, not the tags. In other words, the success rates are lower when based on the number of tags issued. Keep that in mind when you decide which unit to hunt.