Well, part of it is the margaritas I specific. That tangy goodness is going to match well with the general range of spices used in Mexican foods. Fajitas in specific have that bold and spice forward flavor profile that goes well with anything citrusy. Tequila has a fairly distinct flavor that mixes well with that lime and orangey mix. Most people already put lime on fajitas to begin with.

Stuff like guac is fatty enough to benefit from something like that to cut through it as well.

So you’ve essentially got a mouthful of amazing flavors that are used in Mexican food because they go well together.

Some alcoholic beverages are going to work with damn near anything. But if you tried a margarita with your meatloaf, you’d not be as impressed. Not until the fourth or fifth drink anyway.

Something like a low hop beer goes with pretty much any non dessert foods, allowing for personal preference. But you can select bears or wines that would not do well with mexican. Or select for those that would be as good as a margarita. Same with a u cuisine; the right beverage enhances the food, and vice versa.