Why is a Scot's accent so difficult for Americans to understand? [closed]
Solution 1:
Scottish people encounter many people from the UK with different English accents. I suspect that they have become more accustomed to the variety of accents than you have.
Solution 2:
I think a full answer to this question would be rather elaborate, taking in history, geography and politics.
I suspect you were talking to working class Scots. Working class accents are often more localised and have greater variation.
In sort, they can understand you but you can't understand them because you are from a more privileged socio-economic group.