I don't have any linguistic insight, I can only speak comparatively regarding my experience with learning German where it's essentially the same story - strong

I don't have any linguistic insight, I can only speak comparatively regarding my experience with learning German where it's essentially the same story - strong dialects, mumbling and eating sounds make it very difficult (perhaps even more difficult than in English) to understand what the native person is saying. Admittedly, English and German are linguistically similar, so the same effect might be present here as well.