I've never had that happen (sample size ~5). They accept non-citizen patients, so they probably don't make SSN a required field.

(for SSN, never tried to prevent scanning of my ID)

Find a new provider. I have gone 2 decades without providing my SSN to doctors.

In my experience, no one has ever asked it when booking, just when you fill out forms on your first visit. I always leave it blank (and most other things that don't pertain to my healthcare issue) blank and have never been hassled.

I also always ask for a paper copy of the disclosures to sign, saying that "I don't sign blank checks" when asked to sign the electric pad. I've never had an issue with them printing it out, letting me sign, and them scanning it in.

Healthcare "security"/"authentication" is just "protected" by your name and date of birth which is easily discovered for anyone online.

You can just use my SSN: 123-45-6789.