I've done it before. Sometimes a Happy Meal at McDonald's was enough at a decent price. In another topic I noted that I paid $2.99 (plus tax) to buy a King Jr meal at BK using a coupon although the original price is $3.99. At my local location, the costs would have been over $12 ordered a la carte. Part of it is the standardized bundled pricing, where this location has really high a la carte prices.
I used to get deals for free kids meals with the purchase of an adult meal, and when I asked I was usually told they don't have any requirement that a child be there. Some restaurants might actually require a child be present to get a lower priced meal or perhaps some deal. I recall In-N-Out was giving away free hot chocolate to children under a certain age if it was raining. I remember once I took a photo of my kid in the car sleeping while my wife stayed in and they gave me the free deal.
I used to get deals for free kids meals with the purchase of an adult meal, and when I asked I was usually told they don't have any requirement that a child be there. Some restaurants might actually require a child be present to get a lower priced meal or perhaps some deal. I recall In-N-Out was giving away free hot chocolate to children under a certain age if it was raining. I remember once I took a photo of my kid in the car sleeping while my wife stayed in and they gave me the free deal.