“More than one-third of participants felt that daily smoking of cannabis was safer than tobacco, and their views increasingly favored safety of cannabis vs tobacco over time (1742 participants [36.7%] in 2017 vs 2107 participants [44.3%] in 2021; P < .001)”
Probably because it is… Cannabis smoke isn’t that healthy overall, but it’s found to be safer than Tobacco smoke is at least. It doesn’t carry nearly the carcinogenic risks of tobacco, and afaik, it doesn’t carry the same risks for COPD, chronic bronchitis, etc. Though longer term studies would be needed for those to get real data to know for sure.