There seems to be a disconnect here. When I go to Airbnb's help pages, I find the following:
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https://www.airbnb.com/help/article/1237/how-does-it-work-when-airbnb-asks-for-an-id
When you’ll be asked for an ID
This may happen for a couple of reasons. For example, some hosts require their guests to provide a government ID in order to book their place or experience.
There are also times when we’ll ask for an ID to help us confirm you’re really you.
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I've never done Airbnb. But I've always had to show a photo ID whenever I checked into a motel (I know the ID was often photocopied, but I don't remember if it was always photocopied). I thought this was a requirement of the PATRIOT Act to make it difficult for terrorists to travel, but I haven't been able to confirm this with a Google search.
I've always had to provide a credit card (which was scanned) whenever checking in, even when I booked online. I was told that if any towels were missing or damage was found, my credit card would be billed.