The FBI defines terrorism as “the unlawful use of force or violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives.”
Title 22, U.S. Code, Section 2656f(d)(2): Defines terrorism as “premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents.”
Cartels clearly have violence against noncombatants. Cartels clearly have premeditation of violence. Cartels clearly have motivations to coerce or intimidate. The political angle is more unclear. They absolutely seek to destroy political figures which stand against their aims.
The FTO designations under Executive Order 14157 explicitly classify them as such, enabling aggressive counterterrorism measures.
The debate is around if their aims are political or financial.