Well it is technically possible to spend 10 years in a bubble, either academia or professional one, and not learn local language. If your colleagues speak all english, you have non-native partner and don't have motivation to learn it won't come on its own. Not great approach but perfectly realistic.
Don't judge easiness of learning language based on English - its one of the easiest out there to learn (I speak 5 languages and english is absolutely trivial compared to others), especially for folks with similar base (ie roman/germanic ones). Slavic languages are much harder to learn and basically useless outside given country (with few exceptions but usable mostly for C2 or natives level).
Also, compared to many other languages even very basic level of english gets you somewhere, in some languages like French natives basically refuse to speak to you or simply don't understand you unless you have cca B2 level (this is personal experience of me and folks around me where I live)
Don't judge easiness of learning language based on English - its one of the easiest out there to learn (I speak 5 languages and english is absolutely trivial compared to others), especially for folks with similar base (ie roman/germanic ones). Slavic languages are much harder to learn and basically useless outside given country (with few exceptions but usable mostly for C2 or natives level).
Also, compared to many other languages even very basic level of english gets you somewhere, in some languages like French natives basically refuse to speak to you or simply don't understand you unless you have cca B2 level (this is personal experience of me and folks around me where I live)