I see the 16th century man showed up.

All kidding aside, there are some commercial deals that are made with a handshake, but the handshake is simply agreeing to having papers drawn up for legal signatures at a later date. Some sales are made on a handshake but those have to be less than $500. There are also the sale or purchase of securities where all the deals are done with a handshake. All of this is also part and parcel to an oral contract, after the parties agree orally they seal the deal with a handshake and then finalize it with a written contract depending on the circumstances of the deal. But in normal peoples lives where all they deal with loans, contracts, etc is all done with signatures because normal people have a tendency to try to rip others off, a lot of commercial transactions and some sales don't have that issue.