UK Politics

Of course projects will have a bigger ROI if the infrastructure is effective and industry built up in the area meaning it'll effect more people. People won't eat in a restaurant with no windows, broken tables and dirty forks. By only investing in high ROI areas you increase risks of all the economy being hyper focussed in one area and admit you have no idea how to economically develop an area. You also cannot ignore decades of underinvestment and only focus on recent investments. The goal is to activate and connect other economic centres like Leeds and develop new ones. If you have places like Newcastle, Liverpool, Hull connected, you stem the brain drain and allow people to commute or even companies to invest because it won't take 10 years to get to London to work with other companies.

By your posting I can tell you've never spent much time up north or commuted by the rail network and as a result, you're focussed on the information that backs up your world view rather than developing an economic view that is holistic and brings everyone with it rather than further enriches the 12m people in Greater London. Also you discount that if the economy was better developed up north, less outgoings would be on welfare giving more opportunities for a more generous tax regime for companies and the benefits that could bring.

No everything is covered by narrow metrics like ROI, and we haven't even covered ethical considerations like the fact the government has a responsibility to all the electorate and everyone deserves to benefit from good infrastructure. The country got rich on good industry and that wealth ended up invested in the south as the economy moved from industry to services based.