People are paid every two weeks because it's too expensive to pay people daily. I mean too expensive both in the sense of administrative overhead (if people are paid manually) and transaction fees (cheques/EFT fees).

Bitcoin offers the potential to pay people daily or even hourly because transaction fees are reduced to near zero. Here's an interesting article that explores this concept and the idea of paying for performance using Bitcoin/Ethereum: https://medium.com/@spencernoon/paycheck-2-0-385cf6c70ec7.