Ian Campbell 🏴This is a hilariously harmless “fucked around and found out” story.
(edit to add alt text)
tessarakt@neurovagrant The legal criteria for a valid signature (as part of the form "in writing") are pretty specific in Germany: a rendering of the name with at least some recognisable characters.
However, in the US, at least the Uniform Commercial Code: https://www.law.cornell.edu/ucc/1/1-201 defines "Signed" as "includes using any symbol executed or adopted with present intention to adopt or accept a writing .", i.e., also execution by mark.
@neurovagrant But anyway, I doubt there is any legal requirement that the signature has to match the sample on the driver license.
Aren't mortgage papers anyway notarized? So the notary should know what a signature is.
The Lack Thereof 
@tessarakt
Long history in the US to accommodate legal marks made by the illiterate informs our law. Almost forgotten now.
The opening prison scene in the Blues Brothers, where Jake receives his possessions makes a mark rather than signing, is meant to imply that Jake is illiterate.