I have a feeling its not because they know English and they don't speak it on purpose. They genuinely would not be able to speak to the Language. or know a few words and don't feel confident enough. If they are too busy they would not be in a position to help.
This is my experience.
Scandinavia, Netherlands really no problem with speaking English.
France (which I visited 6 times would have been a challenge for sure but my partner is Francophone and one occasion stayed with French people who I knew locally, and spoke English well too, so I could see it in a different way a non French speaking person would have seen it. I noticed even menus are not written in any other languages. However I was wondering alone in a tiny Village in the Pyrenees and I wanted to ask something and the father very quickly called his son who spoke English.
Italy would have been a challenge too, but luckily I speak enough Italian to get by well. I was amazed by Venice tho that its what it seemed that Everyone spoke English there, which was an exception to rest of the Italian cities I visited.
Spain, (well Valencia) I was surprised how unspoken English was. We could not even get by speaking Italian. Its not as close as I was led to believe, but again, in Valencia, I had good experience as the owner of the restaurant and a server did their best to give us directions on a map with sign language. We also met a lovely young lady on a train who conversed the best way she could on the train in English and was very friendly.
Germany I visited with a German friend but that would have been a challenge too if you could not speak the language in my opinion. An old women started angrily yapping away at me when I tried to open a door and I could not read the signs. When I asked him what she was saying he was laughing and told me she said how stupid I was to push and not pull the door.....hmm.
All in all I have the impression that younger people are more open to speak English then the much older....even from the tourists I meet locally. But I believe if you travel alone one has to be ready for the frequencies of ones language according to other peoples experiences by learning a few words as not being able to communicate can really have an impact of how you perceive that city or country you visit.
What is Athens like? I am visiting in October.