My step-mom was involved with specifying such things for her field-service people around 20 years ago. In UPS's case, at least here, they're special-purpose boxes with a bar code scanner, a membrane keyboard, and a crude signature pad. Winders may be under the hood, or in a PC on the truck, but it's different from the general-purpose tablet that Fujitsu's been trying to sell for ages.
But point taken. :-)
Cheers,
Scott.