Not sure if this is why Square required you to sign, but rates for covering fraud are affected by whether you have customers sign or not for credit cards.
Whats the theory behind this? Many people (myself included) just scribble on the receipt because its inconvenient. Merchants never have a problem with this, meaning it could easily be someone who stole my card signing that receipt. Why does this unverifiable, meaningless "signature" change fraud rates?
I've always wondered about this myself as I'm not familiar with dispute resolution for something like this. However, it seems like part of the resolution if an establishment has cameras it seems like they can pull up the frames for the time displayed on the receipt, and present that as evidence that you signed (scribbling shouldn't matter). If it wasn't you in the video then it could be fraud or a friend/relative using your card.
I've only seen investigations for online orders, digital purchases, etc. and not for a restaurant-type setting so it would be interesting to know if video can be used.
If a business claims to collect signatures but doesn't save the receipts/signatures, they'll find it harder or impossible to contest chargebacks. So if nothing else it makes it slightly less likely that banks will eat the charge.