The server has to manually enter it.

Here’s their bullshit workflow:

• Print the check
• Customer reviews it
• Credit card is given to the server
• Card is swiped/authorized at the POS
• Server returns with the receipts
• Customer then writes in the tip amount and signs on the merchant copy
• Server takes the signed receipt and enters the tip amount back at the POS

For whatever reason, the USA keeps using their signature, when the technology for pay at the table has been around for decades.

Meanwhile, chip & PIN has been standard everywhere in Canada for the last decade, with some businesses using it for almost another decade prior to that. Mexico wasn’t far behind either, so it’s absolutely possible to adopt better methods.