I suspect the US system where each of the 50 US states have their own rules for birth certificates, id cards, etc, is the big reason. So, for example, you can

I suspect the US system where each of the 50 US states have their own rules for birth certificates, id cards, etc, is the big reason. So, for example, you can craft fake id for one state...and it doesn't have to be good enough to fool anyone in that state. Just good enough to fool any one of the other 49. Which you then can bootstrap into a "real id" from that second state. Especially given this happened decades ago. It has become much harder over time.