That's not exactly true. Scottish GDP per capita is higher than England and, as an average only beaten by the London area. As part of the union politics; Scottish finances are supressed because Scotland has to pay 10% of all capex expenditure on London projects that are labelled as "UK Infrastructure" (HS2 railway, London tube, london sewer system) whereas English tax payers pay £0 for Scottish capex projects. This is because large scale infrastructure is seen as beneficial to Scots (but not the other way round) - note that the UK parliament has 533 English Members of Parliament and Scotland only has 59. Most acts of parliament seen as beneficial to Scotland are voted down by an English majority (even though it has no bearing on their own constituencies, e.g. The Scotland Bill)
If you look at the National infrastructure plan you'll see that there are no capex projects in Scotland at all, even though each of these projects is subsidised by Scottish taxpayers. The Scottish equivalent is fully funded by Scots taxpayers.