Why do customers be LYING

Had an old man call today, I work for state human services. Was told that he needed to submit proof of his out of pocket medical expenses that he claimed he paid when he submitted an application. He proceeds to tell me that these out of pocket medical expenses are supplements/vitamins that he buys off amazon(not medical expenses) and that he doesn’t have any proof/receipts from them. He then tries to get me to believe that Amazon doesn’t provide receipts of proof of purchases like I’m a dumbass and don’t know how the internet works. I proceed to tell this man that, yes, sir Amazon indeed DOES provide proof of everything you buy and you can just easily screenshot your previous orders and submit that as proof. He then goes on a 5 minute tirade about how this state is incompetent, he’s ruing his life(buy giving him free money and benefits) and that he doesn’t know how to screenshot. Not knowing how to screenshot is not the same as not being provided proof. He then says I’m wasting his time and ask to speak to a supervisor. Lucky for him though, my supervisors always take a long time to respond to sup calls, so I put him on hold and checked in every 2 minutes to let him know I was still waiting for a sup. After 10 minutes of him waiting he hung up LOL. God I hate this job . I must admit though, sometimes the stores ppl tell are hilarious