I'd guess the average English proficiency also varies a lot by the country. I've had lots of elderly relatives who were born before WWII (so in their 80's or 9

I'd guess the average English proficiency also varies a lot by the country. I've had lots of elderly relatives who were born before WWII (so in their 80's or 90's) who have or had, to my knowledge, almost absolutely zero English skills. They might have known "yes" or "no", but that's probably it. You wouldn't have been able to ask them a question and get an answer. Most of them aren't alive any more, of course, and I think most of the ones who are slightly younger than that (those born close to WWII to baby boomers) actually do have at least some knowledge of English. Some are probably fairly close to zero, though, and I wouldn't count most of them as knowing English as a second language. Elderly people living in smaller cities or towns or even in the countryside aren't who you'd be likely to meet as a visitor, of course. But as citizens they exist. You'd probably be hard pressed to find a young person who can't manage to speak any English here, though. I guess that might be more likely in a country like Spain where the local language is globally large enough that you can get by in working life without knowing any English.