Nice reply. I laughed. At the office, when I am asked "Do you really need it?" I sometimes answer: "I don't _need_ my left leg, but I really like it." Same for toilet paper in the stalls.
Cash and bank accounts are two systems in parallel. Cars and public transport (or bicycles, or walking) are systems in parallel. Good clothing and poor clothing are systems in parallel.
A physical driver license and a digital driver license are systems in parallel. Banking/services on a mobile phone and visiting a physical store are systems in parallel.