I’m more familiar with Latin American guerrilla warfare that venerates the peasant class in an attempt to ultimately garner their support for the cause. How similar or different was their approach?
The Viet Cong as an organisation frequently targeted noncombatants; students, monks, priests, foreign medical aid workers--anyone potentially sympathetic to the South and opposed to them--were branded 'war criminals' (Vennema, p. 161-162) and regularly subject to mass murder, as exemplified in the infamous Hue Massacre. After the capture of Hue City during the Tet Offensive, the Viet Cong carried out a policy of 'revenge' against not just those working for the South Vietnamese government but also against civilians politically opposed to the North and even Viet Cong supporters no longer seen as useful to them (Vennema, p. 128).
Furthermore, the Viet Cong would deliberately attack refugees as they were automatically considered anti-communist and thus deserving of murder in their eyes, most infamously during the Easter Offensive in 1972 when they purposely attacked refugee columns and camps with 60mm and 82mm mortars (Vennema, p. 203-204). The Viet Cong's and NVA's treatment of ethnic minorities like the Montagnard was even worse than of Kinh Vietnamese they perceived as political enemies and bordered on genocidal (Kinefuchi, p. 229) with some 85% of their population fleeing as refugees during and after the war (Evans, p. 276).
So, in short, no, the Viet Cong were not "careless"; they very much did care about civilian casualties, which is why they went out of their way to inflict them on "imperialists", "counter-revolutionaries", "class traitors", and others who showed opposition to their ideological goals. Killing noncombatants while prosecuting the war against the South was the feature and not the bug as it was for US and other Coalition forces.
Citations:
Evans, Grant. “Internal Colonialism in the Central Highlands of Vietnam.” Sojourn: Journal of Social Issues in Southeast Asia, vol. 7, no. 2, 1992, pp. 274–304. JSTOR, www.jstor.org/stable/41056853.
Kinefuchi, Etsuko. “Finding Home in Migration: Montagnard Refugees and Post-Migration Identity.” Journal of International and Intercultural Communication, vol. 3, no. 3, 2010, pp. 228–248., doi:10.1080/17513057.2010.487220.
Vennema, Alje. The Viet Cong Massacre at Hue. Vantage Press, 1976.