I doubt there's any AI involved in this. I think they've never bothered to really consider what a fingerprint actually looks like. This is fairly evidenced by how every single phone fingerprint read seems to readily accept many other body parts and I suspect also things that have similar conductivities to human skin.

One place I worked at, the fingerprint reader for security was horrible... you had to get your finger in the exact same position. Sometimes it'd work in the morning, but not in the afternoon after lunch. I thought it was funny how my phone could figure it out, but the building system couldn't... of course the building only took two sample scans, while my phone will take 6 or so.

Maybe the phones are only "figuring it out" by having very loose acceptance criteria for the correct pattern. For all we know, the 6 scans could be mostly marketing fluff to give the appearance of robust matching.

Why should they make sure you only enroll fingerprints? It's not like that happened by accident.