There's a saying, you get what you pay for. Miller Lite is only 3.2g of carbs - but it is also MUCH more watery than the beer with 5g of carbs per bottle.
I tried a Miller Lite with Mexican food in Virginia on a motorcycling trip, after riding Skyline Drive. I have to say the Mexican food was EXCELLENT and I loved it. But the Miller Lite was very watery and didn't add any enjoyment to the meal. There seems to be an off flavor to it. I would have enjoyed several other low carb beers far more than I enjoyed this one.
Yes, it's got fewer carbs. So I suppose you could drink more of them for the same 'carb count'. But for me, I'd rather drink a good beer and enjoy it - especially with Mexican food. It just wasn't worth it to me to drink something watery with little taste.
Low Carb Beer Comparison Chart