Microsoft has decided to help (OK, they smelled money in those missing food servers) and created a device that permanently sits on the table. Redmond is backing this hardware that can take payment, print out a receipt and do it all without having to catch anyone's eye. It allows the tip to be added (minus a deduction for subjecting you to the machine), and it can show various promotions. (OK, so having mandatory TV commercials when you're dining out is probably not a good thing.) It also has a button to summon a manager if there's an issue.
One of the most annoying parts of many a casual restaurant outing is at the end, when you just want to say "Check, please" and all wait staff seem to sense this and decide instead to join the Waitress Relocation Program.