They just don't have the money. As I posted earlier in this thread, the idea is to achieve the kind of productivity levels that Germany has managed since reunification, yet that has taken almost 30 years of everyone paying an extra 5% per month. England in that time has instead championed itself as a comparatively low-tax country, but that has led to enormous underinvestment and ever-widening disparities. Look at the furor that proposed increases on NI and fuel bills are creating; there just isn't the culture to accept tax hikes even if they were universal.
I think deep down the intention is good, and I'm sure all politicians, no matter their hue, would agree that it should be done. How it is done, alas, is where any agreement starts to unravel.