I thought it was quite clear. Verifying your age with an alcohol purchase receipt is a dumb idea for a large variety of reasons, including ease of acquiring one, ease of copying images, ease of printing one yourself and the cumulative ease of doing all this without an actual adult willingly involved in your scheme. It’s is not nearly as fool proof as verifying government ID.

Of course, I’m against all invasive forms of age verification. Doesn’t mean I’m going to advocate for a rally bad alternative either.