I’m not sure your realise just how small Scotland is in terms of GDP and population size compared to England. The population of London alone at 8 million people is larger than Scotland’s population of 5.4 million. Altogether with the rest of the UK their population size accounts for around 8% of the population and a similar level of the UK’s gdp. In addition, Scotland’s sparse population and the widely scattered nation of the population outside the central belt (Glasgow and the aread all the way up to Edinburgh) means that maintaining infrastructure is more expensive per head than England, and they are a net drain on the public purse, not a benefit. Northern Ireland is also a money pit and a chronic liability. If the UK could cut these areas loose there would be a net benefit to the public purse.
The UK is closer to parity with the US than Scotland is to England.
Of course I realize and mean figurally.