It’s difficult to pin down the reasoning here, unless perhaps the workers were foreign nationals. In any event, there is likely an element of turf control: you’ll build when, where, and if the Taliban tell you. “Afghan road workers killed in Taliban ambush,” from BBC News, May 19:
At least 35 construction workers have been shot dead and 20 injured by Taliban insurgents in eastern Afghanistan, an official says.
Eight insurgents were also killed as guards returned fire during Wednesday night’s ambush, a Paktika provincial spokesman told the BBC.
The attack took place in a mountainous district on the highway linking Paktika and Khost provinces.
The Taliban recently declared the start of a “spring offensive” of attacks.