Opposite position here - American Express was the one card I could not use anywhere in my first European trips 20 years ago (don't know it that's changed) - ditched it forever then. MC and Visa works for me. Never looked back.
20 years is a long time! I suggest you give them another shot. I have their Platinum card and the service has been top notch (although paying for their charge card is not required if you pick a product with no annual fee).
Gas pumps will sometimes work after hours even if a clerk isn’t on duty. Same with other self service situations where a card might be your only payment option. Carrying cash is a last resort; you risk losing it or not having enough.
actually this isn't true - i was in Seattle and there's at least one cashless Starbucks and one restaurant (Kati Vegan Thai); when i asked at both places they patiently explained that they couldn't accept cash at either one.