The license process is in depth. It is 6 to 8 weekends of theoretical and practical with a certified instructor You study health, feeding, emergency and first aid, horse structure and equipment, law, traffic rules, etc. etc. Then there is the weekend of "the test". There are 2 judges and you have to orally answer questions and then you have to show your riding skills. My husband and I took the Western but there is also English, Driving, Trail Riding (I think there are also different levels). For the Western we had to dress appropriately and present in-hand at the walk and trot, then mount and perform all gaits and transitions, lead changes, back with turns, side passes, circles, serpentines and navigate trail obstacles. Frankly, it was quite daunting and intense for me as I had to do it in French too. At the end of your performance you have to wait and then the judges call you in and talk with you about what you did right and wrong. Out of our group of 10 only 5 passed. Mostly because of horse training issues. Not only is it time consuming but it is expensive too. You have to "renew" your license every year and it is required for sanctioned competition shows such as AQHA.
At the end you get a card, certificate and a pin to wear. Children can take it when they are 10 years old. Mostly kids take it so they can show since you have to be a licensed 18 or with a licensed adult to ride on the road.
I've never been checked and I don't know anyone who has. I suppose you could get into trouble if there was an accident and you didn't have your license.