One of the problems to address with air and ground transportation is security. After 9/11 (World Trade Center attack in New York) airline security became a nightmare for passengers. First there was the fear of a terrorist attack, then there's the issue of long lines in airports due to security protocols.
It's now common for people to wait for hours, more than 3, just to board an airplane, even if you're just going to a neighboring city. The result is that for short haul flights, one spends more time at the airport than flying. It's now been observed that for short distances in the range of a few hundred miles (which is what we're talking about) Americas requiring connecting flights now prefer to rent a car, and drive to the connecting airport rather than take short flight. It saves the aggravation of missing a flight or being bumped off the airplane arbitrarily by the airline (a new problem in the airline industry).
In Mexico, the issue was more economic, as in the purchasing power of the public, relative to cost of airplane tickets. But they had an additional problem. Crime on the roads spurred by organized crime such as drug cartels, meant that people didn't feel safe driving alone on an old highway for hundreds of miles. Assaults and kidnappings are a possibility on the roads since the 1990s, so the government took account of that in developing a new national road network, that was highly patrolled not just with federal police, but national guard checkpoints, which themselves could be intimidating to drivers. The busses solved all of the problems of safety, because people felt safer traveling in numbers. New roads, fancy buses, small efficient bus stations that looked like airports did 40 years ago. Easy to get in and travel with near point to point efficiency.
