I live in a major city where people also don't use cash. Some older people still do, but absolute most transactions are cashless, especially if you'd ask eg a coffee shop or a restaurant. It is about 99:1 - 97:3 ratio of cashless:cash.

Internet outages are extremely rare and are fixed in just about an hour, be it a major backbone outage, a bank server outage, or a local wire cut. In this case, most cafes will switch to a mobile hotspot connection.

Not an issue, and wasn't for like last 10 years. I honestly don't remember when I had cash on me.