>>1773925My autistic brother, you don't seem to have yet realized that successful social interaction isn't about saying all the right things or doing all the right things, it's just about how you make the other person feel.
The only aim is to make the other person feel relaxed and comfortable, what you actually do is almost completely irrelevant.
Conversations are awkward because you make them awkward by acting awkward.
This interaction wasn't awkward because you messed up her change, it was awkward because you were probably acting like a nervous sperg throughout the whole thing and making her feel uncomfortable.
Chad could have wasted all of her money, then broken the machine and have to get an assistant to come fix it, but it would still be a good social interaction if he was chilled out about it and cracking jokes. Might even be the highlight of her day because it would be a funny story to tell.
