[deanc]

Why citizens and not permanent residents?

[dotancohen]

For the same reason that married couples enjoy privileges that dating couples do not. The long term commitment and investment in a partner indicate and confer interest in long term stability and development.

[deanc]

So a permanent resident who has lived in a country, for say, 10 years? You don't think they're committed at that point and should have a right to vote on the society they are contributing to?

[RandomLensman]

Are there no differences in obligations between the two (e.g., draft)?

[maccard]

It’s going to wildly depend on the countries, but between the UK and Ireland, no.

You do have to swear allegiance to the monarchy in the UK, which some people may feel more or less positively about.