My guess is because Mexico is broken down by state. Don't want those Cancun all inclusive guests feeling unsafe...
Ironically most of the recent issues I've heard of have been cartel assassinations at those same resorts around Cancun and Tulum. There are definitely areas of Mexico I'd avoid driving through but I can't remember ever feeling unsafe during my travels there.
Update from the State Dept on Mexico.
https://travel.state.gov/content/tr.../traveladvisories/mexico-travel-advisory.html
See state summaries and advisory levels below for information on your specific travel destination. Some areas of Mexico have increased risk of crime and kidnapping.
Country Summary: Violent crime – such as homicide, kidnapping, carjacking, and robbery – is widespread and common in Mexico. The U.S. government has limited ability to provide emergency services to U.S. citizens in many areas of Mexico, as travel by U.S. government employees to certain areas is prohibited or restricted. In many states, local emergency services are limited outside the state capital or major cities.
U.S. citizens are advised to adhere to restrictions on U.S. government employee travel. State-specific restrictions are included in the individual state advisories below. U.S. government employees may not travel between cities after dark, may not hail taxis on the street, and must rely on dispatched vehicles, including app-based services like Uber, and regulated taxi stands. U.S. government employees should avoid traveling alone, especially in remote areas. U.S. government employees may not drive from the U.S.-Mexico border to or from the interior parts of Mexico, except daytime travel within Baja California and between Nogales and Hermosillo on Mexican Federal Highway 15D, and between Nuevo Laredo and Monterrey on Highway 85D.
Read the country information page for additional information on travel to Mexico.
The Centers for Disease Control and Prevention (CDC) has determined Mexico has a high level of COVID-19. Visit the CDC page for the latest Travel Health Information related to your travel.
Do Not Travel To:
Colima state due to crime and kidnapping.
Guerrero state due to crime.
Michoacan state due to crime and kidnapping.
Sinaloa state due to crime and kidnapping
Tamaulipas state due to crime and kidnapping.
Zacatecas state due to crime and kidnapping.
Reconsider Travel To:
Baja California state due to crime and kidnapping.
Chihuahua state due to crime and kidnapping.
Durango state due to crime.
Guanajuato state due to crime and kidnapping.
Jalisco state due to crime and kidnapping.
Morelos state due to crime.
Sonora state due to crime and kidnapping.
Exercise Increased Caution When Traveling To:
Aguascalientes state due to crime.
Baja California Sur state due to crime.
Chiapas state due to crime.
Coahuila state due to crime.
Hidalgo state due to crime.
Mexico City due to crime.
Mexico State due to crime.
Nayarit state due to crime.
Nuevo Leon state due to crime and kidnapping.
Oaxaca state due to crime.
Puebla state due to crime and kidnapping.
Queretaro state due to crime.
Quintana Roo state due to crime and kidnapping.
San Luis Potosi state due to crime and kidnapping.
Tabasco state due to crime.
Tlaxcala state due to crime.
Veracruz state due to crime.
Exercise Normal Precautions When Traveling To:
Campeche state
Yucatan state