You can enter into a contract with even less than a signature (ie: just by accepting payment you can inadvertently end up in a contract), so the idea that a signature wouldn't work except in very specific cases seems pretty weird to me.

I've had very few wet-ink, notarized signatures required of me. Some documents are weird though ie: a picture won't be accepted, but a scan will be, etc.

God it's all so fucking stupid.