LJ
That’s the point MRA4 didn’t actually cost the government £3.5bn pounds. That may be the headline figure, however they paid £3.5bn and then get x million/billion straight back in taxes via corporation tax, income tax, national insurance, plus VAT and petrol duty etc from all of the workers spending.
Therefore the real cost to the government is much lower. It’s the same when a government says it’s going to give NHS staff or the military a pay rise of x%. Everyone goes that’s really good aren’t the government being generous. But their not because they know they will already recoup a certain percentage straight back in income tax and NI. So the actual cost to the government isn’t as high as the headline figure may suggest
However by buying of the shelf from a foreign company they will see nothing back. So what they pay is the bottom line and UK plc will not benefit.
Also what happens when you want a bit of kit that’s not "off the shelf" then what are you going to do. Where are you going to go and how much do you think that nice foreign company is going to charge for it.