Hmmm.

 

I once, maybe in 2005, I had to fill out and sign in black ink for US government.
Also every letter in the signature had to be legible as that letter.
I suspect this was because early Copier machines could not reliably copy other colors ?

I like the idea of g in blue ink because then you can easily see the original from a copy.
Of course this was before Color Copiers were invented.
Though I think businesses still use black/white copiers.

 

In the Philippines it's normally required to sign in black.