A couple of other book recommendations , if he will read them.
"Think Like a Pancreas" and "The Ultimate Guide to Accurate Carb Counting", both Gary Scheiner . I have them on my smart phone too for quick lookups, along with the GoMeals app (essentially, the CalorieKing book) to look up things at restaurants, etc. It also has all the fast food places.
I agree with the comments above...at his age he will be out often with friends, eating out, etc and he cannot rely on you to do his management for him.
There are lots of simple approximations that will get him close....he needs to learn,
for example, that a closed fist size pile of mashed potatoes or rice is about a cup and this is about 30g of carb, etc. With learning a few approximations for common food like this, you can be shown a plate of food and quickly make some estimates. Yes, it wont be as good as weighing it out on a food scale or looking at a package, but many times it will be good enough. Even with labels and weighing there are lots of errors.
The books above will teach him these approximation techniques and/or he can take a class. Then he will be free to go wherever and have the confidence he can manage things.
I was shocked to see a grown teenager at my diabetes center who still had his parents giving him injections....how dependent that must make him feel!